Explanation: Prior to any potential distress, a GMDSS radio operator must be prepared to act swiftly and accurately. All the listed actions (A, C, and D) are critical operational practices that ensure an efficient and effective response in an emergency, making option B the correct choice. * **A) Creating a table of DSC coast stations:** Knowing the available Digital Selective Calling (DSC) coast stations along the vessel's route is fundamental for directing distress alerts to shore-based rescue coordination centers (RCCs) within range. * **C) Preparing detailed Distress message files:** Pre-programming distress messages on satellite and MF-HF SITOR (NBDP) equipment saves vital time and reduces errors during a high-stress situation, ensuring critical information like vessel ID, position, and nature of distress is transmitted quickly. * **D) Ensuring LES choices are correct and updated:** Properly selecting and updating Land Earth Stations (LES) for satellite communications ensures distress alerts are routed to the correct Rescue Coordination Center (RCC) responsible for the vessel's current Search and Rescue (SAR) region, enabling a prompt and targeted response. These preparatory steps are essential for maximizing the chances of a successful rescue in accordance with GMDSS regulations.