Hello Henry! glad you are enjoying my lectures.

A. the point is not that he is perceptive... pretty obvious stuff

B. not really a lack of confidence... he's intimidated

C. correct^^

D. the opponent is actually less able than he appears

If you look at the answers, from A to D, 

A and B are about the narrator.

C and D are about the opponent.

The question is about the opponent, so it's more likely that C or D is correct. 

AND...^^

The topic of the question is not just the opponent, but the description of him.

The question is not asking about the author's impression of the young man.

All the aforementioned information adds up to C.

Hope that helped... thanks for asking and if you have further questions don't hesitate.

 Cheers, Steve