What type of check should be transmitted to confirm a radio is operating properly?

The correct choice is related to specific radio communication checks used to ensure functionality. A 10-40 check is specifically designated to verify that a radio is operating correctly. This check might involve confirming clarity, volume, and overall transmission quality during communication. In the context of radio communication protocols, utilizing the 10-40 indicates to all parties involved that a status report on the radio's performance is being conducted, ensuring that operators can rely on their equipment in critical situations.

In contrast, the other options represent different types of radio checks or communications. Each of those serves other purposes and does not specifically address confirming the operational status of a radio device. Therefore, the relevance of the 10-40 in this scenario underlines its role as a dedicated assessment tool within procedural radio communication.