The correct answer is that the ScrumMaster says nothing. Caves are set up for team members who need isolation and quiet for a short time; they might work quietly or have a private conversation or meeting. The other answers are not accurate
descriptions of a cave’s purpose. It’s ok to use a cave for a short period of time to get some quiet; there’s no requirement that caves just be used for private conversations. That said, the use of caves should not be overused.