Many elementary schools have after-school programs for students. Most of the students (1)[participate / participating] in (2)[it / them] cannot go home when school ends because both parents work. These students are too young to stay at home alone. (A)       the main purpose of them (3)[are / is] just to take care of the children until their parents can take them home. The best part is that many of them are free for parents, (4)[unlike / like] professional daycare centers (5)[what / that] are usually very expensive. While the children are there, the teachers in charge of the programs want them to do something, (B)        

(6)they may arrange (7)them for children to do (8)[their / its] homework.

1. (1)-(5), (8)에서 어법상 적절한 것은?