The submarine may seem like a feat of modern engineering, but the history of submersible boats is far older than many people would believe. The 1) earliest mentions of a submarine is dated to the 16^th century, when two men submerged in a river and demonstrated the abilities of their vessel by bringing a torch, which stayed lit, on their journey. 2) However, this recorded event started the evolution of the modern submarine that we all know today.

3) Submarines were not put into any major use until the early 1900s. By then, the invention of numerous innovations such as torpedoes, battery-driven propulsion, and a pressurized cabin 4) was pivotal for the submarine to become military-oriented craft. In World War I, the submarine became 5) very important; the U-boat is a figure that almost 6) anyone who are familiar with military history will know.

1) earliest mentions of a submarine is

The submarine may seem like a feat of modern engineering, but the history of submersible boats is far older than many people would believe. The 1) earliest mentions of a submarine is dated to the 16^th century, when two men submerged in a river and demonstrated the abilities of their vessel by bringing a torch, which stayed lit, on their journey. 2) However, this recorded event started the evolution of the modern submarine that we all know today.

3) Submarines were not put into any major use until the early 1900s. By then, the invention of numerous innovations such as torpedoes, battery-driven propulsion, and a pressurized cabin 4) was pivotal for the submarine to become military-oriented craft. In World War I, the submarine became 5) very important; the U-boat is a figure that almost 6) anyone who are familiar with military history will know.

2) However

The submarine may seem like a feat of modern engineering, but the history of submersible boats is far older than many people would believe. The 1) earliest mentions of a submarine is dated to the 16^th century, when two men submerged in a river and demonstrated the abilities of their vessel by bringing a torch, which stayed lit, on their journey. 2) However, this recorded event started the evolution of the modern submarine that we all know today.

3) Submarines were not put into any major use until the early 1900s. By then, the invention of numerous innovations such as torpedoes, battery-driven propulsion, and a pressurized cabin 4) was pivotal for the submarine to become military-oriented craft. In World War I, the submarine became 5) very important; the U-boat is a figure that almost 6) anyone who are familiar with military history will know.

3) Which of the following best introduces the paragraph?

The submarine may seem like a feat of modern engineering, but the history of submersible boats is far older than many people would believe. The 1) earliest mentions of a submarine is dated to the 16^th century, when two men submerged in a river and demonstrated the abilities of their vessel by bringing a torch, which stayed lit, on their journey. 2) However, this recorded event started the evolution of the modern submarine that we all know today.

3) Submarines were not put into any major use until the early 1900s. By then, the invention of numerous innovations such as torpedoes, battery-driven propulsion, and a pressurized cabin 4) was pivotal for the submarine to become military-oriented craft. In World War I, the submarine became 5) very important; the U-boat is a figure that almost 6) anyone who are familiar with military history will know.

4) was

The submarine may seem like a feat of modern engineering, but the history of submersible boats is far older than many people would believe. The 1) earliest mentions of a submarine is dated to the 16^th century, when two men submerged in a river and demonstrated the abilities of their vessel by bringing a torch, which stayed lit, on their journey. 2) However, this recorded event started the evolution of the modern submarine that we all know today.

3) Submarines were not put into any major use until the early 1900s. By then, the invention of numerous innovations such as torpedoes, battery-driven propulsion, and a pressurized cabin 4) was pivotal for the submarine to become military-oriented craft. In World War I, the submarine became 5) very important; the U-boat is a figure that almost 6) anyone who are familiar with military history will know.

5) very important

The submarine may seem like a feat of modern engineering, but the history of submersible boats is far older than many people would believe. The 1) earliest mentions of a submarine is dated to the 16^th century, when two men submerged in a river and demonstrated the abilities of their vessel by bringing a torch, which stayed lit, on their journey. 2) However, this recorded event started the evolution of the modern submarine that we all know today.

3) Submarines were not put into any major use until the early 1900s. By then, the invention of numerous innovations such as torpedoes, battery-driven propulsion, and a pressurized cabin 4) was pivotal for the submarine to become military-oriented craft. In World War I, the submarine became 5) very important; the U-boat is a figure that almost 6) anyone who are familiar with military history will know.

6) anyone who are

A number of this type of 7) German vessel was used to sink Allied vessels and harass shipping lines. For example, the sinking of the Lusitania, among other civilian boats, 8) were often cited as a factor in the United States entering World War I. A British passenger ship, the Lusitania was struck by a torpedo from a German 9) U-boat. Over 100 Americans were killed. This incident sparked indignation from the American people, who called for a declaration of war. Clearly, the advent of the U-boat 10) has changed the scope of the naval theater of war.

7) German vessel was used

A number of this type of 7) German vessel was used to sink Allied vessels and harass shipping lines. For example, the sinking of the Lusitania, among other civilian boats, 8) were often cited as a factor in the United States entering World War I. A British passenger ship, the Lusitania was struck by a torpedo from a German 9) U-boat. Over 100 Americans were killed. This incident sparked indignation from the American people, who called for a declaration of war. Clearly, the advent of the U-boat 10) has changed the scope of the naval theater of war.

8) were often cited as a factor

A number of this type of 7) German vessel was used to sink Allied vessels and harass shipping lines. For example, the sinking of the Lusitania, among other civilian boats, 8) were often cited as a factor in the United States entering World War I. A British passenger ship, the Lusitania was struck by a torpedo from a German 9) U-boat. Over 100 Americans were killed. This incident sparked indignation from the American people, who called for a declaration of war. Clearly, the advent of the U-boat 10) has changed the scope of the naval theater of war.

9) U-boat. Over 100

Which choice best combines the sentences?

A number of this type of 7) German vessel was used to sink Allied vessels and harass shipping lines. For example, the sinking of the Lusitania, among other civilian boats, 8) were often cited as a factor in the United States entering World War I. A British passenger ship, the Lusitania was struck by a torpedo from a German 9) U-boat. Over 100 Americans were killed. This incident sparked indignation from the American people, who called for a declaration of war. Clearly, the advent of the U-boat 10) has changed the scope of the naval theater of war.

10) has changed