i would go with semicolon
Answer:
charity/ nonprofit organization
Explanation:

are<u> </u><u>singing</u><u> </u>

Since, in the sentence we can see that the action is continuing. Hence its present continuous tense.
The above sentence is about present continuous. Here two actions are happening. One is "listening" and the other is "are singing".

I would say that your answer or the answer is creditable and true