Explanation: A Distress message, signified by the word "MAYDAY" spoken three times, is the highest priority transmission in radio communications. For it to be effective and actionable, all the listed information is absolutely critical. * **Name of vessel (A):** Identifies *who* is in distress, allowing responders to confirm the station and potentially access details about it. * **Location (B):** Provides the fundamental information needed for rescuers to *find* the distressed party. Without a precise location, assistance cannot be rendered. * **Type of distress and specifics of help requested (C):** Explains *what* is wrong and *what kind* of help is needed. This allows responders to understand the severity of the situation, deploy appropriate resources (e.g., medical, fire, search and rescue), and prepare for the specific emergency. Omitting any of these details would severely hamper rescue efforts or make the distress call ineffective. These requirements are codified in international radio regulations to ensure that critical emergency information is conveyed clearly and concisely, maximizing the chances of a successful rescue. Therefore, all information listed is mandatory.