What is the most common type of antenna for GMDSS VHF?

Correct Answer: Option D — None of the above

VHF antennas for GMDSS are typically vertically polarized, omni-directional whips. None of the listed options—horizontally polarized circular or long-wire antennas—are standard for maritime VHF, as they would fail to provide the required uniform horizontal coverage and would be physically impractical for the high frequencies used in VHF.