학교 기출문제입니다. (천재 김덕기 중3 문제입니다)

she gets very busy on weekends when people bring their pets to her shop.
다른 형태로 고친것중 올바른 것을 모두 고르시오.(관계부사 문제입니다)

1) she gets very busy on weekends people bring their pets to her shop on.
2) she gets very busy on weekends on people bring their pets to her shop.
3) she gets very busy on weekends on that people bring their pets to her shop.
4) she gets very busy on weekends on which people bring their pets to her shop.
5) she gets very busy on weekends which people bring their pets to her shop on.

제가 알기론4,5번은 맞는데족보기출문제에 1번도 정답이라고 되어 있는데 혹시 잘못 된것은 아닌지 궁금합니다.

여러분들의 조언을 구하고자 합니다. 4,5번이 맞느냐 1,4,5가 맞느냐 문제입니다.