Ana lucía le duele el ojo. ella debe a. tomar un aspirina. c. correr en el partido. b. usar muletas. d. ponerse gotas.

This sentence is given using the reflexive pronoun for the third person singular, which is se. We use Reflexive Pronouns with a verb to point out that a person carries out an action to or for himself or herself. Here this reflexive pronoun has been attached to the end of the verb. This is only true if the verb is not conjugated, such as infinitives or gerunds or if the verb is an affirmative informal command. Finally:

Ana Lucía le duele el ojo. Ella debe ponerse gotas