"It's obvious that the students ______ early to sleep well."
The question wants you to fill in the blank with a reflexive verb, acostarse (to go to bed). A reflexive verb describes an action that is performed on a subject.
The subject in this sentence is 'los estudiantes', which is third-person plural. The reflexive article used will be 'se', because the students are the ones going to bed. The conjugation for 'acostar' in this sentence will be acuestan.
