Question

15. Choose the Spanish equivalent of "They are."

Answer 1

B. Ellos son.

Explanation:
Ellos translates into a masculine or mixed-gendered “They”. Son just means are.
Nosotros is out because it’s like a “we” and same goes for vosotros.
Es means is more than it means are.
Estos means these.

Answer 2

B) Ellos son because we are talking about multiple people referring to other people