Final answer:
The Master officially relieves you of the conn when they C) specifically inform you that they have the conn, ensuring a clear transfer of responsibility.
Step-by-step explanation:
The student is asking about the point at which a ship's Master officially takes over the control, or 'conn', from another officer on the bridge in a situation of traffic congestion at sea. According to maritime traditions and practices, the correct answer is C. The Master specifically informs you that he has the conn. This means the Master would explicitly state that they are now taking control of navigating the vessel. It is a formal acknowledgement of the transfer of responsibility from one officer to the Master, ensuring clarity and preventing any misunderstanding.