Answer:
C) the inherent danger of a leader who exhibits signs of madness.
Explanation:
EDG2020
An appositive phrase gives you an alternative description or more information about a noun, and it is separated from other elements in the sentence by commas.
The appositive phrase in this sentence is "a whiz at foreign languages" - you can identify it because it is describing and giving you more information about Mr. Wilson (the proper noun the phrase is next to) and has commas around it.
William Shakespeare interests me the most