Right answer:
tarea
Tarea is a noun that means homework. Recall that a noun is a word or group of words that is the name of a person, a place, a thing, or activity or a quality or idea. This noun means schoolwork that a student is required to do at home. Thus, the students have a lot of homework in the biology class. On the other hand, nota means note, regla means rule and banda means band. Finally:
Los estudiantes tienen mucha tarea en la clase de biología.