Answer:
In order to successfully complete this exercise, you have to fill-in the blanks with an appropriate possessive adjective in Spanish, taking into account the hints provided in brackets. Note that you have to pay attention to the gender and number of the nouns to which the possessive adjectives make reference in order to choose the correct one.
Step-by-step explanation:
Tus (Your, fam.) libros están en la mesa.
Es su (their) nieto.
Nuestros (Our) abuelos son simpáticos.
Es mi (my) primo.
Sus (His) tíos son de Perú.