Question

they are (estar, masculine/mixed)
ser
yo estoy
nosotros
somos
ellos
están

Explanation:

The question is about the conjugation of the verb "estar" for the subject "ellos" (masculine/mixed plural "they"). Among the options, "Ellos están" is the correct conjugation of "estar" for "ellos" in the present tense. "Ser" is a different verb, "Yo estoy" is for "yo" (I), and "Nosotros somos" is the conjugation of "ser" for "nosotros" (we).

Answer:

Ellos están