The answer is b, empezamos.
The answer is (usted) because you dont have a personal relationship with this person.
ustedes means you guys
vosotros means all of us
tu is used for someone whom you are close with like a family member or someone whom you have know for a while.
A short story of you real life
Incorrect; the correct way is “Estoy escuchando música.”
Answer:
Esta
Explanation:
Sofia: Esta Señora es mi tía Ana, la hermana de mi padre.