For the first one (the "most weaken" Q), here you go!
The question here asks which finding would most weaken the author's position. Our natural next question, then, is "what IS the author's position?"
With questions like this, I like to summarize the main argument as simply as possible: the author's position seems to be "it's bad for doctors to lie to patients." We could elaborate on that specifically if we wanted (since the fourth paragraph focuses on the benefits of truth to patients, the fifth paragraph covers the impact of honesty/lies on patient autonomy, and the sixth paragraph goes beyond patients to discuss the impact on the doctor, other doctors, and the profession), but we can still summarize the whole thing super simply as "it's bad for doctors to lie to patients."
This is a good start! Unfortunately, it usually isn't enough (and it isn't enough here), because multiple answer choices weaken this idea. Our challenge is to find the answer choice that weakens that position in a way relevant to what the passage actually said, specifically how the passage author made this argument.
Looking at the answer choices one by one:
A: This one directly weakens the argument in paragraph 4, which said that "truthful information...helps patients cope with illness" and then followed up with some examples of physical outcomes that were better for patients who were told the truth. In contrast, choice A says that a physical outcome (symptom severity) is better for patients who don't acknowledge the truth about their condition. So A at least does weaken the argument.
B: This one is laying a classic AAMC trap - it's trying to get you to care about a reasonable-sounding tangent. That is, we look at B and it makes logical sense, but in reality, the passage wasn't about whether patients realized they were being deceived at all: it was about whether lying was bad for them in general. Put another way, if we imagine that B is totally true (and that most patients who are lied to don't realize it), the entire last three paragraphs of the passage could still make complete sense, since it could still be true that when patients ARE told the truth, they do better. So this one doesn't weaken the passage argument. Watch out for wrong answers like this one, they're very common!
C: This one is really convoluted in a way that almost makes it tempting. It's tempting because it seems to be saying "the truth led to this bad outcome (false hope)." But the AAMC really, really values directness - that is, they want an answer choice that undermines what the passage is directly saying. The passage was saying that doctors telling patients lies is bad, and doctors telling patients the truth is good. The passage didn't say anything about patients guessing the truth. So this one is out. (If we wanted to really dig into this one, we might realize that for someone to guess the truth, they must not have been told the truth in the first place. So really, this is just a negative impact of dishonesty, which is totally in line with what the passage says.)
D: This is another tempting one, but the passage never said that patients who are told the truth don't become less cheerful. More importantly, the passage only said that being told the truth is better for patients in general. It's very possible that patients who are told the truth DO become less cheerful, but they're still better off than patients who were lied to. (To sum up, this one is wrong because cheerfulness is not the same thing as well-being.)
So in a quick summary:
A is right because it does weaken the main argument.
B focuses on something that sounds good but wasn't actually the subject of the passage argument.
C focuses on something that wasn't actually the subject of the passage argument, but that is complicated enough to tempt us.
D narrows in on a tiny thing (cheerfulness) that isn't representative of the larger concept at stake (overall patient well-being).
