A power-driven vessel leaving a quay or wharf must sound what signal? （）

A.alternating red and yellow light
B.alternating white and yellow light
C.all-round white or yellow light
D.all-round white light only

A.The fishing vessel must keep clear of the vessel not under command
B.If the vessel not under command is a power-driven vessel，she must keep clear of the fishing vessel
C.They must exchange whistle signals
D.Both vessels are required to take action to stay clear of each other