You can use facts and then use fallacies over them. There's no advantage in making your argument appeal only to emotions if it can easily fall apart by logic. And refusing to accept any other argument might show that you don't really believe in your argument and people might understand that you're afraid of being wrong.
An argument without logical fallacies is solid and based on firm logic. It makes sense and cannot be destroyed simply. The correct answer is:
C. By making your argument sound more credible
