Serios is the correct answer
in the first one I guess it doesn´t exists a correct answer, so you can mark whatever you want.
in the second one you have to put your name and age(sentence 1), write two things that you would like to do(sentence 2), next you have to write why would you like to do such activities(sentence 3) and in the fourth sentence you could you these example:
Hace mucho que no juego tenis.
Ellos perdieron el patio de su casa después de que el volcán comenzó a erupcionar.
Los juguetes son nuestros
