Billy called out to John, and listened for what?
Options:
- silence
- response
- communication
- hanging up
- whisper
Let's think carefully first. Step-by-step reasoning process:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
A call usually has a response. One can listen to a response. Response means an answer. So the final answer is response.