A Client Is Monopolizing a Group Session,not Allowing Other Members

A client is monopolizing a group session,not allowing other members to participate.What is the most appropriate way to address the client?

A) "You are not allowed to speak for the remainder of the session."
B) "You are selfish and must leave now."
C) "You are very rude when you act this way."
D) "You need to stop this behavior.Let's see what others have to say."