Which of the following frequencies have been designated for "On-scene" communications in the Global Maritime Distress and Safety System?

Correct Answer: Option D — VHF Ch-16 and NBDP on 2174.5 kHz.

On-scene communications under GMDSS are coordinated using designated frequencies. VHF Channel 16 is used for voice radiotelephony, while 2174.5 kHz is the standard frequency for Narrow Band Direct Printing (NBDP) to facilitate text-based distress and safety communications between units involved in the rescue.