The answer is the first option: popular appeal.
Popular appeal - or appeal to popularity - is a logical fallacy in which something is assumed to be good/true/valid or, in this question's case, easy because most people are doing it.
The logical process followed here would be:
1. You and other people are taking the same class.
2. The other people were able to pass.
3. You are able to pass.
As we can see, it does not necessarily lead to a true and correct conclusion.
