Gabriel: hola marianela, ¿qué onda? ¿cómo estás?
marianela: chévere y tú ¿qué haces?
gabriel: nada, por aquí con los muchachos. ¿y qué es de rosa?
marianela: ¡oye! ella es mi hermanita. ¡mucho ojo con ella!
gabriel: ¿yo? , ¡no manches! , tu hermanita es muy linda pero es muy chiquita.
marianela: bueno, pues yo sólo te aviso, mira que sería muy mala onda si la lastimaras.
gabriel: bueno, todo está chido. ¿amigos?
marianela: amigos
¿quién es rosa?
la amiga de marianela
la hermana de gabriel
la novia de gabriel
la hermanita de marianela

La hermanita de Marianela.

Explanation:

You have to read the whole text and then, you have to answer the question that says "who is Rosa?". In English the text says the following:

Gabriel: Hi Marianela, what's up, how are you?

Marianela: All right and you? What do you do?

Gabriel: Nothing, I'm around here with the boys. And How is Rosa?

Marianela: Hey! She is my little sister. Very careful with her!

Gabriel: Me? Don't stain! Your little sister is very pretty but she is very small.

Marianela: Well, I just warn you, look it would be very bad if you hurt her.

Gabriel: Well, everything is cool. Friends?

Marianela: Friends.

Who is Rosa?

Marianela's friend

Gabriel's sister

Gabriel's girlfriend

Marianela's little sister

So as you can see, the text says that Rosa is Marianela's little sister.

i don't know sorry sir