Answer:
The correct answer is C.) Ellos.
Step-by-step explanation:
Los amigos translates to "the friends". Nosotros means we, and since this sentence is about "the friends", we would not use nosotros. You would not use ustedes to talk about friends. Ellas would not be used either because "los" in this phrase means there are only boys (or boys and girls). Ellas is used when there is a group of only girls.
Hope this helps,
❤Nicki❤