I need help on all these

Ill put the number, the answer, and then put why in (there)

4 Prima (I am the cousin of my cousin) (feminine because says la ___)

5 Primo (I am the cousin of my cousin) (masculine because says el ___)

6 Sobrino (My brother is the nephew of my aunt) (masculine

because hermano)

7 hija (I am the daughter of my mother) (feminine because says la ___)

8 sobrina (My sister is the niece of my uncle) (feminine

because hermana)

9 hijo (I am the son of my father) (masculine becase says el ___)

answer: the answer is b. se quejan because it's in the plural form.