The correct answer is 'much'. In the English Language, when comparing two things, we use the comparative form of the adjective. In this case, 'wiser' is the comparative form of 'wise'. You can add the adverb "much" to show that James' wisdom exceeds those of his friends to a large extent. The addition of 'more' in options A and B makes them grammatically incorrect as wiser is already in its comparative form. You add 'more' to only adjectives that have three or more syllables (e.g. beautiful, excellent, etc). You cannot use more and '-er' for the same adjective. Therefore the answer is D. 'much'.