Final answer:
Macbeth uses the analogy of the snake and eating in fear in Act III, Scene 2, to express his worry about his own safety as king, which corresponds to option A.
Step-by-step explanation:
In Act III, Scene 2, lines 15–20 of Shakespeare's Macbeth, Macbeth refers to the analogy of the snake and eating in fear to express his worry about his own safety and the dangers of his position as king. The correct answer is A. Macbeth has attained the throne through regicide and fears the retribution and the instability of his ill-gotten power. His paranoia is fueled by the need to protect his kingship, leading him to contemplate further violence to secure his position. This is in contrast to earlier in the play, where his ambition was the driving force; now, it's his concern for security and the consequence of his actions. Therefore, he likens his uneasy state to that of living in fear, as if he has eaten the insane root like Banquo mentions earlier in the play, which has made him prisoner to constant anxiety and suspicion.