Explanation: DSC (Digital Selective Calling) radios use a unique 9-digit MMSI (Maritime Mobile Service Identity) number for selective communication between stations. To perform a radio check with a specific coast station, the system requires a direct address. Option C is correct because DSC radios include a dedicated "TEST" function designed for this purpose. Entering the specific Coast Station's MMSI number ensures the test call is directed only to that station, preventing unnecessary alerts to other vessels. This is a standard procedure under GMDSS (Global Maritime Distress and Safety System) for verifying equipment functionality without initiating a distress or urgency call. Option A is incorrect because the button under the red plastic cover is specifically for initiating a Distress alert, a severe emergency signal, and not for routine radio checks. Misusing it can trigger an unnecessary emergency response. Option B is incorrect because DSC systems use MMSI numbers for selective calling, not FCC call letters. While stations have call letters, the digital addressing relies on the MMSI. Option D is incorrect because "ALL SHIPS" is a broadcast call to all vessels within range, typically for safety or general announcements, not for a private, directed test with a specific coast station.