Explanation: Vessel personnel detect a SART (Search and Rescue Transponder) using their ship's X-band radar. The SART, when interrogated by the radar's pulse, transmits a unique signal on the radar's 3-cm wavelength (9 GHz band). This signal appears on the radar display as a line of 12 equally spaced dots, radiating outward from the SART's actual position along its line of bearing. This distinctive 12-dot pattern precisely indicates the SART's location and direction. A) Incorrect. VHF-FM Ch-70 is the Digital Selective Calling (DSC) channel. SARTs do not transmit on this frequency. B) Incorrect. While AIS-SARTs exist and use AIS, a traditional SART operates as an X-band radar transponder. The question refers to the specific detection method of a SART's characteristic radar response. C) Incorrect. While heavy seas can affect signal strength, the unique *pattern* used for detection is the 12-dot signal, not just its intermittent appearance.