Why is A not the right answer? I don't see any indication of how society "generally" treats physicians. What I do see is "'various' efforts to cut medicine down to size," which is not enough to infer how society generally feels.
My problem with D is equivocation. Specific Knowledge could refer to an actual listing of the types of knowledge trades are based or it could just mean the "mere know-how," which is knowledge specific to any one trade.