Answer:
Could be either A or C depending on what they're asking. A is asking if the person wants them to list them into ballet and C is asking if the person already listed themselves for the ballet class.
Explanation:
I'm not very good on explaining this but I'll give you an example or more than one.
Antonio y yo nos besamos.
Antonio and I kissed each other.
¿Os conocéis?
Do you all know each other?
Juan y María se casaron.
Juan and Maria got married (to each other).
Los estudiantes se ayudan.
The students help each other.
I hope it helped
