I didn't understand this problem, and just chose (C) and moved on. I don't really get why (A) is the correct answer.
This was my thought-process:
So since this is a principle example question, no need to look for the core. The principle that I extracted from the argument was something like: experts are chosen/picked on their persuasiveness.
Honestly, I thought all the answer choices were attractive but (A)!
So with (A), I thought it was missing the major point: someone is chosen over someone else. It just says successful politicians are not always the ones who best undersatnd how to help their country. and the whole next part about "some lack insight...election campaign" didn't sound like anything similar to the main argument. Or is "chosen" not what is important???
Now that I look at (C)... the part "despite the fact that an audience may be more affected by..." is going against the evidence, right? Since the main argument is saying that experts need to know how to make convincing presentations since they are evaluated by JURIES -- so it is important to take into consideratino the juries (audience) part, whereas (C) says the opera singer with the best voice is chosen even if the audience may be more affected by someone else.
I'm just very confused.. What would you say the general principle is just looking at the argument anyway???? I don't know how "general" or "narrow" I need to extract the principle from the argument.