The statement that provides the best analysis of the metaphor Macbeth uses in his soliloquy in Act 1, Scene 7, lines 1-28 is:
c Macbeth compares murdering the king to a “poisoned chalice” because the act could, ultimately, cause his own demise.
In this soliloquy, Macbeth grapples with the consequences of his ambition and the moral implications of killing King Duncan. The metaphor of the "poisoned chalice" encapsulates the idea that while the act might bring temporary power or fulfillment of his ambition, it carries the risk of severe and potentially deadly repercussions for himself.