The answer is D - present perfect tense. A would be - gave. B would be - gives. C would be - had given.
When did<span> the transformation of the American military from a citizen based ideal to a .... It is the intention of this thesis to highlight the profound </span>impact<span> that the </span>War<span> of 1812 had ... 1784-1898 focused on the</span>s oldiers<span> and officers away
from </span>war<span>.
</span>
The answer is : D
Because in order for the essay the be organized you have to make sure the paragraphs are on topic and the topic is clear