How does the effect known as "bank suction" act on a single-screw vessel proceeding along a narrow channel?

Correct Answer: Option C — It pulls the stern toward the bank.

Bank suction is caused by the restricted flow of water between the hull and the bank, creating a low-pressure area along the quarter. This pressure differential draws the stern toward the bank, which can cause the bow to swing violently away if not corrected by timely rudder application.