To signify that message was received and understood?

• A. Roger
• B. Over
• C. Out
• D. Emergency

Answer: (A)

In railroad radio etiquette, the word used to show that a message was heard and understood is Roger. It serves as a clear acknowledgment that you got the instruction and grasped what was being asked or directed. Using Roger keeps the channel concise and confirms comprehension without implying action yet. If you intend to act on the instruction, you’d typically follow with a statement that you will comply, such as Wilco, or another phrase indicating action.

Contrast with the others: Over means you’ve finished transmitting and expect a reply, Out means you’re finished and no reply is expected, and Emergency signals a urgent situation requiring immediate priority. So Roger is the standard way to acknowledge understanding of the message.