While the ideal pedagogical purpose of homework is to reinforce and review learning (as in option B), this question's key points to a different, more practical aspect from the teacher's perspective.
Class time is limited. Teachers need to cover new topics, explain concepts, and conduct activities during school hours.
By assigning tasks like practice exercises or reading as homework, teachers can ensure that this essential part of the learning process happens outside of class.
This effectively outsources the time needed for practice and drill, which reduces the teacher's in-class workload of supervising these tasks.
This allows the teacher to use class time more efficiently for instruction. From this practical viewpoint, reducing the teacher's in-class burden is a significant purpose of homework.