This is how your sentences will look: (Given that they are in present tense)
Usted quiere un gato.
Mis hermanas visitan a mis padres.
The second answer. Because “sus” is the only one which has the “s” because it is plural. If it would be “nuestro” it should had an “s” like “nuestros hijos son altos” or “tus hijos son altos”
Do you need that translated ?
