The logical fallacy used in the passage is D. Ad hominem attack.
Here's why:
1. Ad hominem means attacking the person making the argument rather than addressing the argument itself.
2. In this passage, the speaker attacks the opponent's academic performance (receiving Cs and Ds) rather than discussing their abilities to be a class president.
3. By focusing on the opponent's grades, the speaker is trying to discredit the opponent personally, which is a common characteristic of an ad hominem attack.
4. Instead of addressing the opponent's qualifications directly, the speaker uses the opponent's academic performance to undermine their credibility, which is a fallacious way of arguing.
