Explanation: MMSI (Maritime Mobile Service Identity) numbers are nine-digit identifiers used in DSC (Digital Selective Calling) for various entities. The first digits of an MMSI indicate the type of station or call. For a DSC call to a specific group of vessels, the MMSI must begin with a single zero (0). This '0' signifies that the call is directed to a predefined group rather than an individual vessel or a shore station. Following the '0' are three digits representing the Maritime Identification Digit (MID) of the country coordinating the group, and then five digits uniquely identifying that particular group. Option D, **030327931**, correctly fits this format. It starts with a single '0', indicating a group call, followed by '303' as the MID, and '27931' as the group's unique identifier. Options A and C (003664523 and 003036483) begin with '00', which designates an MMSI for a coast or shore station, not a group. Option B (338462941) begins with '3', indicating an individual vessel's MMSI, where '338' is the MID.