Answer: Aggregate
Explanation: All these people who found themselves in the same place because of a certain occasion, and at the same time of course, but in that case, these people are most likely to see each other for the first time, or if not for the first time then they may have seen each other earlier in the passage, but there is no no connection between them.The only connection is that they are in the same place at the same time. It is an aggregate, therefore not a group of people, because all these people are caught by the music playing by these two musicians, so they stopped to hear them but are not connected to each other. Same as in a restaurant or market.