What is meant by the term “radio silence”?（）
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
