Felix, by saying "10-4" to dispatch, was indicating that he received and understood the communication or instructions given to him based on the new information from the 911 operator. It is a code commonly used in radio communication to acknowledge the message and signal comprehension without needing to provide a lengthy response.
In this context, "10-4" was Felix's way of confirming to dispatch that he got the additional instructions and was ready to act upon them. It is a way of ensuring clear and effective communication between Felix and dispatch without the need for elaboration or unnecessary back-and-forth exchange of words.
So, the correct answer to the question is:
C. He received and understood the communication.