On offshore drilling units，each EPIRB or SART must be tested once every（）.

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

A.It informs survivors that assistance may be nearby
B.It informs survivors when the battery's charge condition has weakened
C.It informs survivors when the SART switches to the standby mode
D.It informs survivors that a nearby vessel is signaling on DSC

A.The SART's blips on the PPI will begin arcing and eventually become concentric circles
B.The DSC unit will react to the SART's signal and respond with the two-tone autoalarm
C.The SART can provide an approximate location to within a two nautical mile radius per IMO standards
D.The SART signal appears as a target which comes and goes; the effect of heavy swells on a SART