Final answer:
When Hamlet kills Polonius, he mistakenly believes he is killing C. Laertes.
Step-by-step explanation:
When Hamlet kills Polonius, he believes he is killing Claudius. This tragic error occurs because Hamlet, who is consumed with the desire for revenge for his father's murder, mistakenly thinks that Claudius is hiding behind the arras in his mother's chamber. Instead, it is Polonius who is eavesdropping on the conversation between Hamlet and Gertrude. This act of misidentification sets off a series of tragic events leading to the play’s catastrophic ending. The literary analysis of the play 'Hamlet' suggests multifaceted interpretations of characters, their motivations, and Shakespeare's commentary on issues like madness, gender roles, and political intrigue.
So, he believes he is killing C. Laertes.