Chemotherapy and Psychological Support - Kaplan NEW

Clearly C

C is incorrect because the opinions of doctors are irrelevant. B strengthens the argument because it eliminates one possible weakener - that the patients who did not attend did not do so because they were too ill.

Thanks for correcting me!
but I not sure about, how B is correct. Can you please amplify your explanation for B.

Strengtheners do not "Prove" an argument, they simply make it more likely to be true. If I were going to argue with the author, one way I would attack is to say that maybe the people who didn't participate were too sick to do so. That would mean the sample (participants who CHOSE to use psychotherapy) were not representative of the total population and therefore the conclusion cannot be applied to the total population. By ruling out that road of attack, we make the conclusion more likely.

I Got it! Thanks.

Just got to know that OA is B

C is a trap.

This one is very confusing .
seems far fecthced .