Question

we are (estar)
ellas son
vosotros estáis
nosotros estamos
yo estoy

Explanation:

To conjugate the verb "estar" for the subject "we" (nosotros in Spanish), we use the form "estamos". Among the options: "Ellas son" uses "son" (from "ser") and is for "they (feminine)"; "Vosotros estáis" is for "you all (informal, Spain)"; "Yo estoy" is for "I". So the correct form for "we" with "estar" is "Nosotros estamos".

Answer:

Nosotros estamos