a, Explanation: The doctor himself tells Macbeth that Lady Macbeth must cure herself of her "mind diseased." Choice b is illogical. The fact that one person sleepwalks does not show that people in the Middle Ages were more prone to sleepwalking than they are today, and it makes little sense that they would be. Choice c is contradicted by the details in the play. Shakespeare's depiction of Macbeth, Lady Macbeth, and Macduff—among others—shows a vast understanding of emotional distress. Choice d is not supported by any details in the play.
