Tu because If you put Mi or mis son rojos it says my are red which dosen't really make sense. Since you put tu in front of son (plual) it would be they are red.
Estamos is the correct answer :)
Answer:
Nosotros somos de la escuela.
Explanation:
Hope it helps!!
Nariz, nose in spanish is nariz.
A. ellos no estan enfermos hoy
