How would you pass a red buoy in the maritime buo

How would you pass a red buoy in the maritime buoyage system “A”？______.

A.keep the buoy on the vessel’s starboard side when approaching a port and on the vessel’s port side when leaving

B.keep the buoy on the vessel’s port side when approaching a port and on the vessel’s starboard side when leaving

C.keep the buoy on the vessel’s starboard side when approaching and leaving

D.keep the buoy on the vessel’s port side when approaching and leaving

请帮忙给出正确答案和分析，谢谢！