单项选择题
A.call for help and keep the individual in sight
B.run to the radio room to send an emergency message
C.immediately jump in the water to assist the individual
D.go to the bridge to report the captain
单项选择题 （）is the most visible signal of distress from a lifeboat at sea in the daytime.
单项选择题 Which signal is recognized as a distress signal?（）.
单项选择题 A RADIO SIGNAL FROM A DISTRESSED VESSEL AUTOMATICALLY DIRECTED TO A RCC GIVING POSITION，IDENTIFICATION，COURSE AND SPEED OF THE VESSEL AS WELL AS THE NATURE OF DISTRESS is known as（）.