Explanation: An Emergency Position Indicating Radio Beacon (EPIRB) is specifically designed to meet the criteria described. Upon a vessel sinking, these devices are designed to automatically release from their hydrostatic release unit, float free, and activate. Once activated, they transmit a distress signal, typically on 406 MHz, which is picked up by satellites and relayed to rescue coordination centers, pinpointing the vessel's location. Answer B is incorrect because while EPIRB is the correct device, the listed frequencies are either outdated (2182 kHz for legacy voice distress) or incorrect (405.025 kHz instead of the primary 406 MHz). Answer C, a bridge-to-bridge transmitter, is for direct communication between ships and requires manual operation; it does not float free. Answer D, an auto alarm keyer, is a component that transmits an alarm tone to attract attention to an incoming distress call, not a standalone distress beacon.