Final answer:
The appropriate verb in the conditional mood to fill in the blank is 'deberían'.
Step-by-step explanation:
The appropriate verb in the conditional mood to fill in the blank in the sentence is deberían.
In this sentence, 'Los estudiantes' is the subject, which means 'The students' in English.
The verb 'deberían' conveys the idea that the students should ask for forgiveness from the teacher. It is formed by taking the verb 'deber' (meaning 'to should' or 'to owe') and adding the conditional ending '-ían'.
Learn more about verb conjugation in Spanish