Explanation: Radio silence during a distress incident is imposed by the authorities responsible for coordinating the search and rescue (SAR) effort. The **On Scene Coordinator (OSC)** is the person designated to coordinate activities at the actual scene of a distress incident. They have direct control over communications among responding units. The **Rescue Coordination Center (RCC)**, chosen by the **SAR Mission Coordinator (SMC)**, is the shore-based authority responsible for overseeing the entire SAR mission. These entities are empowered to impose radio silence on relevant frequencies to ensure that distress and SAR communications are clear and unimpeded, preventing interference from non-essential traffic. * **A) Land Earth Stations (LES)** are part of satellite communication systems and relay alerts, but they do not have the authority to coordinate SAR operations or impose radio silence. * **C) Public Correspondence Coast Stations** handle general maritime traffic and may relay distress calls, but are not the coordinating authority for SAR. * **D) The first responding vessel** provides initial assistance but does not possess the overall authority to command radio silence for the entire SAR operation.