Final answer:
Macbeth suffers from guilt and fear.
Step-by-step explanation:
In lines 18-28 of Macbeth, Macbeth suffers from guilt and fear.
Macbeth's affliction is described in the text as the multiplying villanies of nature that swarm upon him. The reference to battles, horrors of war, and the fever of doubtful news indicates that Macbeth is haunted by his guilt and filled with fear over the consequences of his actions.
Therefore, the correct answer is a) Guilt and fear.