Final answer:
After the narrator in 'The Black Cat' undergoes a change for the worse, he begins abusing his wife and his cat, Pluto.
Step-by-step explanation:
In Edgar Allan Poe's short story The Black Cat, after the narrator undergoes "a radical alteration for the worse," he starts exhibiting increasingly violent and cruel behavior. The correct answer is A. He starts abusing his wife and favorite cat, Pluto. This change in behavior signifies a descent into madness and the loss of the narrator's humanity, leading to a series of tragic and horrifying events.