The correct answer is A) The Rescue Coordination Center (RCC) controlling the distress communications. The RCC is responsible for coordinating and managing all distress communications and rescue efforts. Once the distress situation has been resolved and communications have ceased, the RCC must transmit a message to inform all parties that the distress is over. This ensures that the emergency response is properly concluded and all resources can be stood down. The other options are incorrect because the vessel or Coast Radio Station that initiated the distress communications do not have the authority or responsibility to officially close out the distress case - that falls under the purview of the RCC overseeing the incident.