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.
Uno de los principales componentes de la autonomía es la responsabilidad.
Cuando no les dejan hacer determinadas tareas por si mismos,pensando que no son responsables.
Espero y sirva de algo:)
B. Sacapuntas, it means pencil sharpener while the rest relate to computer.
