Answer:
A. Replacing the word "defend" with "help"
Step-by-step explanation:
"Help" is more emotional word than "defend". Use of the word "help" implies that the party/country being helped is weak and needs someone, while the word "defend" does not give any clue to whether the party/nation being defended is weak or not, and whether they really need it or not. Hence replacing the word "defend" with "help" would create a strong emotional appeal to the audience.
Option B is incorrect because replacing the word "gathering with "hoarding" will make the speech sensational but not emotional.
Option C is incorrect because replacing the word "Americans" with "citizens" will make it ambiguous.
Option D is incorrect because replacing the word "weaponry" with "armaments" would only tell a bit more about kind of weaponry, with almost no effect on emotional appeal.