Me llamarás por la mañana? a. sí, me llamaré b. sí, los llamaré c. sí, te llamaré.

This is an interrogative sentence with the verb llamar (to call) in future with the 2nd person singular tú (you), although the subject tú is not explicitly here (because is a Tacit Subject).

By logic, if a question is done with the subject tú, the answer must be with the subject yo (I).

The conjugation of the verb llamar in future with the 1st person singular yo (I) is llamaré.

Hence, the answer to the question:

¿Me llamarás por la mañana?  

Will you call me in the morning?

Is:

Yes, I will call you

The other options are incorrect because they do not agree with the subject of the

Sí, me llamaré  

Yes, I will call me

Sí, los llamaré

Yes, I will call them