Passage A brings up a rival view – relativist historians. But the reference to propaganda isn’t related to countering their view. And in Passage B, there is no mention of a rival approach to historical scholarship. Even if we accept that Passage B is implicitly arguing against the view that historians should be neutral, the mention of propaganda doesn’t support that implicit argument. Passage B mentions propaganda simply to contrast historical scholarship with a kind of writing that isn’t objective.

(B) doesn’t accurately describe anything either passage does anywhere. Neither passage suggests other fields involve more bias. And, if you are tempted by (B) because you consider “propagandists” to be part of a different field from historians, that’s not why the authors mention propaganda. Propaganda is not a separate field with different kinds of scholars; it is a kind of writing that isn’t objective.

Arguably both passages consider propaganda a “type of scholarship,” although we might quibble with this. Passage B in particular might distinguish between scholarship and propaganda. Let’s set this issue aside. A cleaner reason to eliminate (C) is that neither passage suggests propaganda has “recently” been discredited. They both consider propaganda as something to avoid, but there’s no indication that it has only been discredited in recent times.

(E) is a very tempting answer, especially because “contrast” might have been a word we used ourselves in describing Passage B, and because on a superficial analysis, (E) seems to accurately describe something each passage does in connection with mentioning propaganda. But, the question is not merely whether each passage does (E). It's whether (E) is the primary purpose of mentioning propaganda.

Does Passage A mention propaganda for the purpose of contrasting propaganda with other kinds of persuasive writing? No. The author's goal isn't to help us understand the range of persuasive writing out there and how propaganda compares to those different kinds of persuasive writing. The author's purpose is to describe a kind of writing that historians should not engage in.

Similarly, Passage B doesn't mention propaganda for the purpose of contrasting it with other kinds of writing. It brings up propaganda as a kind of writing that historians need self-discipline to avoid. The whole passage is directed toward what is required in order to write scholarship as opposed to propaganda. Passage B wasn't merely trying to tell us that propaganda is different from other writing and why. So, even if you think (E) accurately describes something that happens in connection with each passages' reference to propaganda, it fails to accurately describe why each passage mentions propaganda.