单项选择题

While on watch at sea you must maintain a proper lookout at all times. You are on a 200-foot cargo vessel with an unobstructed view astern from the steering position. The vessel is being hand-steered during daylight hours in good visibility and clear of any navigational hazards. The lookout may be().

A.the helmsman
B.the officer on watch
C.either A or B
D.neither A nor B