Final answer:
The correct verb form is 'recuerde.'
Step-by-step explanation:
The correct verb form that completes the sentence is recuerde.
In this context, the verb form needs to agree with the subject ella, which is third person singular. The correct conjugation of the verb recuerdar (to remember) for third person singular is recuerde.
For example, you can say: No pienso que ella recuerde la letra de la canción (I don't think she remembers the lyrics of the song).
Learn more about Spanish Verbs