Correct answer:
c. me pongo
This sentence is given in reflexive form because it uses the reflexive pronoun that matches the first person singular me and a verb in simple present. We use reflexive pronouns with a verb when pointing out that a person carries out an action to or for himself/herself. So here I'm the person that carries out the action that is related to thinking in the last athletics competition. Finally:
Sí, yo me pongo a pensar en la última competencia de atletismo mucho, me vuelo loco.