Final answer:
Macbeth fears Macduff because of his loyalty to King Duncan and his potential threat to Macbeth's rule. Macduff's moral integrity and opposition personify the dangers Macbeth faces as a usurper.
Step-by-step explanation:
In Shakespeare's play Macbeth, Macbeth expresses fear of only one man in Scotland, who is Macduff. He perceives Macduff as a threat due to his undoubted loyalty to the late King Duncan and potential opposition to Macbeth's rule. This fear is deeply rooted in Macbeth's guilt over his own treacherous actions, as well as his increasing paranoia about securing his throne against possible contenders. Macbeth's apprehension about Macduff aligns with the option D in the multiple-choice question. Macduff's loyalty to Duncan and his potential to challenge Macbeth stem from the themes of betrayal, power, and the consequences of one's actions that are central to the play.
Macbeth's fear is not without reason. Macduff ultimately represents a significant threat to Macbeth, being someone with a strong moral compass and the capacity to rally others against Macbeth's tyrannical reign. Furthermore, Macbeth's anxiety towards Macduff is heightened after Macduff flees to England to support Malcolm, Duncan's son, in raising an army against Macbeth, indicating a direct challenge to his authority.