I think the answer is A)He combines details and indisputable facts with hyperbole and
understatement to demonstrate the complexities of attempting to unify
forces in order to promote change among opposing groups of citizens.
but I am not 100% sure since I have not read "Letter from a <span>Birmingham Jail" in a couple of years.</span>
Ad hominem is an attack against the arguer instead of the argument itself in order to cast doubts about arguer's argument.