What indicates that the M16A3/M4A1's chamber is empty while in Condition 3?

In the context of the M16A3/M4A1 and its operating conditions, recognizing the status of the chamber is critical for safe handling. Condition 3 specifically refers to a scenario where there is a magazine inserted, but no round is chambered.

When the weapon is in Condition 3, the safety being on is an indication that the rifle is in a ready but safe position for handling. This status does not guarantee a round is chambered, and thus understanding the safety features is essential.

Having the safety engaged while in Condition 3 emphasizes the importance of controlling the weapon and ensuring it is not accidentally discharged. The other options do not correctly convey the status of the chamber being empty; for instance, a round in the chamber and a magazine inserted would indicate the rifle is in a different condition. Therefore, the safety being on is the indicator of proper handling when the chamber is confirmed to be empty.