Question

Presume that Hamlet did know that Claudius was listening to his talk with Ophelia. What sentence do you think Hamlet might have specifically intended Claudius to hear?

Answer 1

be a nun, go to nunnery, and leave this cruel world where there is no love, where wife betrays her husband, where BROTHER KILLS BROTHER

Answer 2

"Are you genuine?", "Are you reasonable?" are the lines which Ophelia did not by any stretch of the imagination comprehend why he was inquiring. This implies these lines are coordinated to Polonius.

"It hath made me frantic" was said for them to trust that he's extremely insane.