Final answer:
The banquet scene in Macbeth showcases his mental decline as he is visibly tormented by guilt and hallucinations, notably failing to conceal his instability from his guests.
Step-by-step explanation:
The banquet scene vividly portrays Macbeth's mental decline through his overwhelming guilt and hallucinations. During what is supposed to be a noble gathering, Macbeth is haunted by the ghost of Banquo, which only he can see. This supernatural event exacerbates the guilt and fear Macbeth has been harboring since he murdered King Duncan and Banquo.
His public reaction to the ghost, characterized by fear and agitation, cracks his regal facade, revealing the psychological torment beneath; this scene is a stark contrast to his earlier displays of false confidence and deliberate deceit.
Lady Macbeth attempts to control the situation, but her efforts are futile as the guests witness Macbeth's unraveling sanity, marking this as the point where he can no longer conceal his inner turmoil. Consequently, the correct answer to the question is b) Macbeth is overwhelmed by guilt and hallucinations.