Final answer:
Hamlet reveals his melancholy to Rosencrantz and Guildenstern through a critique of the world around him, expressing deep disillusionment without explicitly citing his mother's actions or the ghost's visit as causes.
Step-by-step explanation:
In Act 2 of Hamlet, the reason Hamlet gives for his melancholic disposition to Rosencrantz and Guildenstern is not overtly clear. He expresses a deep sense of despair and disillusionment with the world, describing it as "a sterile promontory" and "a foul and pestilent congregation of vapours." The conversation suggests that Hamlet's underlying distress stems from his contemplation on the frailty and futility of human existence, but he does not directly mention the cause of his mother's remarriage to his uncle or the ghostly visitation which has charged him with the task of vengeance. The complex layers of his emotional state are further discussed in literary criticism, such as T.S. Eliot's essay Hamlet and His Problems, which explores the intense feelings of Hamlet and the difficulty Shakespeare faced in conveying them through art.