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.
Èl es muy alto y fuerte.
Ella no está en el hospital.
El restaurante recibe el vino.
Tu eres bonita.
Lave los platos, tambien limpie la casa. Doble la ropa para toda la familia y empeze in Hardin.
