Answer:
A.
Step-by-step explanation:
Ad hominem is a logical fallacy that involves a personal attack. An argument based on the perceived failings of an adversary rather than on the merits of the case.
The only argument that is attacking the adversary is the option A, where it is implied that other companies are deceiving you. That is not relevant to how Lima Bean Green Toothpaste can give you a better smile. So that's why it's defined as a ad hominem fallacy.