Decide if you should use tú or usted when speaking to the following person. your little sister

tú
usted

Decide if you should use tú or usted when speaking to the following person.

your mother's boss

tú
usted

A new girl at school asks you, "¿Cómo te llamas?" Which of the following is the best response to this question?

Muy bien, gracias. ¿Y usted?
Nos vemos.
¿Qué tal?
Me llamo __(your name)__.