In radio communication, what does '10-4' commonly signify?

In radio communication, '10-4' is commonly used as a code to signify "OK" or to acknowledge a message that has been received and understood. This phrase serves as a clear and concise way to confirm that instructions or information have been comprehended without ambiguity.

The use of '10-4' is particularly important in emergency and law enforcement communications, where quick and efficient exchanges are crucial. It allows for effective communication, ensuring that all parties are on the same page, without the need for lengthy explanations.

The other codes in the choices represent different meanings that don’t align with the established use of '10-4'. For instance, commands to stop or proceed with caution have their specific phrases or codes that convey those directions but do not include '10-4'. This helps to maintain clarity and simplicity in radio communication.