Final answer:
Lady Macbeth purposes to persuade Macbeth to murder King Duncan and solicits spirits to make her cruel. She does not arrange an ambush; she plans to murder the king in his sleep.
Step-by-step explanation:
The question revolves around Lady Macbeth's actions and intentions after reading Macbeth's letter regarding the witches' prophecies and learning about King Duncan's visit to their castle. The correct statement pertaining to Lady Macbeth after these events is that she does indeed purpose to persuade Macbeth to commit regicide (1), and she also asks spirits to 'unsex' her and fill her with cruelty (2). However, she does not arrange an ambush on King Duncan; instead, she formulates a plan to murder him in his sleep and frame his chamberlains for the deed (3). Therefore, the statement that is not true of Lady Macbeth is that she arranges an ambush on the king.