¿me compraste las manzanas? a. sí, te las compré b. sí, me las compré c. sí, te los compré

First of all, I give a positive answer to this question saying Sí, te las compré. The word sí is used when answering a question in an affirmative way. Keep in mind that the letter i has an accent mark. On the other hand, te is the indirect object pronoun for the second person singular. An Indirect Object Pronoun is a person that receives the action of a verb indirectly. Its purpose is to tell you to whom or for whom something is done. So you receive the action of the verb indirectly. Moreover, las is the direct object pronoun for the third person plural (feminine form because manzanas is a feminine plural noun). A direct object pronoun replaces a direct object, that is a noun that directly receives the action of a verb in a sentence. So this noun is las manzanas. Therefore, we replace las manzanas by las. Finally:

- ¿Me compraste las manzanas?

- Sí, te las compré