The correct answer is B) It pulls the stern toward the bank. When a single-screw vessel is proceeding along a narrow channel, the effect known as "bank suction" causes the stern of the vessel to be pulled toward the bank. This is because the rotating propeller of the single-screw vessel creates a low-pressure area near the stern, which in turn creates a suction force that pulls the stern toward the nearby bank. The other options are incorrect because: A) the bow is not pulled toward the bank, C) the entire vessel is not pushed away from the bank, and D) the vessel does not heel toward the bank due to this effect.