
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".

Not A because of Ave. not C because Sept, and D just sucks. B is your answer.
To briefly state the author's purpose for writing the text you are analyzing
I think you forgot to put the pictaure of the quotes