What plan do Polonius Claudius and ophelia now put into action?

Polonius, Claudius, and Ophelia devise a plan to observe Hamlet's behavior and determine the cause of his apparent madness. They decide to use Ophelia as bait, encouraging her to interact with Hamlet while they secretly watch their encounter. This scheme aims to gather evidence about Hamlet's feelings and mental state, ultimately to confirm whether his madness is due to his love for Ophelia or if there are other underlying reasons.