GMDSS vessels equipped for A2, A3 or A4 must maintain a continuous DSC watch on 2187.5 kHz.
Official USCG Answer & Rule Citation
Correct Answer: Option D — At all times when underway.
SOLAS Chapter IV regulations mandate that vessels operating in sea areas A2, A3, or A4 must maintain continuous automated digital selective calling watchkeeping on the MF distress frequency 2187.5 kHz at all times while the vessel is underway.
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