As part of his research on the Civil War, Charlie is reading a book about ironclads (a type of boat) and how they revolutionized naval warfare.

The correct answer to this open question is the following.

Here there is no question, just a sentence. What is your question?

Trying to help we did some deep research and can comment on the following.

The question that is missing is this: "Which of the following is most likely a lens he is exploring?" And unfortunately, you also forgot to include the options for this question.

As part of his research on the Civil War, Charlie is reading a book about ironclads (a type of boat) and how they revolutionized naval warfare. The lens. Which of the following is most likely a lens he is exploring?

the lens of technology.

This is correct because ironclads were a major advancement in the technology of war. Ironclads were modern ships for the time that used steam to move, They were constructed in 1859 and played an important part during the actions of the American Civil War.

the triple alliance. germany and austria-hungary were already allies by 1879 when, worried about a threat from russia, they formed the dual alliance. italy joined the group in 1882. there was a concern about a possible attack from france and the alliance needed powerful friends to defend it.

the speech convinced americans that the ussr was an enemy, rather than an ally, which led to the creation of the truman doctrine.