How can vessel personnel detect the operation of a SART in its vicinity?（）

A.A unique radar signal consisting of a blip code radiating outward from a SART's position along its line of bearing

B.A unique two tone "warbling" signal heard on VHF-FM ch-70

C.A unique two tone alarm signal heard upon the automatic unmuting of the 2182 kHz radiotelephone automatic watch receiver

D.The SART signal appears as a target which comes and goes; the effect of heavy swells on the SART