Final answer:
Seyton serves as Macbeth's chief attendant when his thanes abandon him.
Step-by-step explanation:
The correct answer is C) Seyton. In Shakespeare's play Macbeth, as his thanes are abandoning him, Seyton stands by Macbeth as his chief attendant. Characters like Banquo and Macduff become Macbeth's adversaries. Banquo is murdered upon Macbeth's orders, and Macduff is a primary force against Macbeth, leading to his eventual downfall.