The effect known as "bank cushion" acts in which of the following ways on a single-screw vessel proceeding along a narrow channel?

Correct Answer: Option D — It forces the bow away from the bank.

Bank cushion occurs when restricted water piles up between the vessel's bow and the near bank. This asymmetric hydrodynamic pressure zone creates a high-pressure cushion that forces the bow away from the bank toward the centerline of the channel.