Explanation: GMDSS regulations, specifically SOLAS Chapter IV, stipulate essential radio equipment for survival craft to facilitate rescue. For passenger ships and cargo ships of 500 gross tons and above, the required equipment includes: * **Three Survival Craft Transceivers (SCTs):** These are portable, waterproof VHF transceivers used for on-scene communication between survival craft and rescue units. * **Two Search and Rescue Transponders (SARTs):** These devices emit a series of twelve dots on an X-band radar display when interrogated by a ship or aircraft radar, indicating the survival craft's position. Option B correctly states these requirements for the specified vessel types and tonnages. Options A, C, and D are incorrect because they misstate the quantities of equipment or apply them to the wrong vessel tonnage categories, which have different requirements (e.g., cargo ships between 300-500 GT typically require two SCTs and one SART).