Question

Part 1 of 1 - question 20 of 60 2.0 points hoy mi hermano cumple 35 años; es...
a.mi cumpleaños
b.tu tamaño
c.su cumpleaños
d.nuestra fiesta

Answer 1

c. su cumpleaños

it would not be "mi" cumpleaños for it is not your birthday. B. would not make sense in this case. And the final option would be if both your brother and you were to be sharing a party.