What is NOT a distress signal?（）

A.Stations not directly involved with the on-going distress communications may not transmit on the distress frequency or channel
B.Stations remaining off the air to safeguard proprietary information
C.Two three-minute silent periods，at 15 and 45 minutes after the hour，that provide a transmitting "window" for distressed vessels to transmit distress alerts using J3E
D.Communications on a distress frequency or channel is banned for 24 hours following the cessation of the distress traffic

A.Distress and alarm signals transmitted or intercepted
B.Times of beginning and end of watch period
C.Routine navigational traffic
D.Daily statement about the condition of the required radiotelephone equipment

A.The vessel would arrive at the distress scene more than 36 hours after the receipt of the initial distress message
B.There are vessels closer to the distress scene that are proceeding to assist
C.The Master of the vessel in distress has requisitioned another vessel，and that vessel has accepted the requisition
D.You are on a tank vessel and the distress involves a major fire on board the other vessel