Explanation: When radio silence has been imposed during a distress situation, routine communications cannot be resumed until explicitly authorized by the controlling authority. This authority is typically the Rescue Coordination Center (RCC) or the station controlling the distress traffic. **D) Routine communications can resume after the Rescue Coordination Center transmits a message on the frequency indicating the cessation of distress.** This is correct because international radio regulations (e.g., ITU Radio Regulations, GMDSS procedures) dictate that once radio silence is declared (often using the "SEELONCE MAYDAY" or "SILENCE DISTRESS" message), it can only be lifted by the station that imposed it or the designated controlling station. This is done with a specific message, such as "SILENCE FINI" or "PRUDENCE," indicating the distress is over or control has been relinquished. **A) After determining that the frequency or channel appears to be no longer in use.** This is incorrect. "Appearing" to be clear is insufficient. A formal announcement from the controlling station is required to officially lift radio silence. **B) After determining that geographic distance from the Distress situation will prohibit any other signal from interfering.** This is incorrect. Radio silence is a formal regulatory directive, not just a practical assessment of interference risk based on individual station distance. All stations are bound by the imposition until it is formally lifted. **C) If, in the master's opinion, communications on that frequency will interfere with emergency communications.** This is incorrect. This statement describes a reason *to impose* radio silence, not *to resume* routine communications. The question asks when routine communications can resume, and a master's opinion alone cannot lift a universally imposed radio silence.