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

A.An emergency boat and crew
B.A siren or rotating flashing light
C.Flashing red lights located one-half mile upstream and downstream of the facility
D.Buoys with flashing lights controlled from shore，located one-half mile upstream anddownstream of the facility