Difference between C and D

C is the correct answer here. The best way to do this one is to negate the answers and see what that does to the argument. If we negate D, we see "A nation that is a world leader cannot necessarily borrow from another nation even if that other nation does not set the terms of the dealings between the two nations." This does not destroy the argument, and is just off course. You can eliminate it just by thinking "that does nothing to this," and moving on. If we negate C, we see "A nation that has the terms of its dealings with another nation set by that nation can be a world leader." See how that would destroy the argument? The assumption, then, is C, that a nation cannot be a leader if the terms of its dealings are set by the other country.

What kind of strengthen question is this? I thought you only negate Strengthen with a necessary premise questions and I thought this was a Suff.Premise Question. Thank you!

@smilde11 this is a Strengthen with Necessary Premise question. Notice the question stem: "The reasoning in the passage ASSUMES which one of the following?" Strengthen with Sufficient Premise questions will include "follow logically", "properly concluded", "properly drawn", etc. Hope that helps! Please let us know if you have any other questions.