Answer:
D. Ad hominem fallacy
Step-by-step explanation:
Ad hominem is a fallacy that is characterized by avoiding genuine discussion of arguments and instead attacking the opponent's character, motives or other personal attributes. This focuses the discussion on the characteristics of the person making the argument and not on the quality of the argument itself. In this case, the author is criticizing the character of the opponent by calling him "wealthy upper middle class American slob" and making fun of his arguments, instead of engaging with him fairly.