"물건을 줍는 남자"
Translation:The man that picks up an object
It's not enough for "the man WHO picks up an object" just to be accepted. "The man THAT picks up an object" is just plain wrong. The fact that the word "that" is the preferred answer instead of "who" is all the more troublesome. This is a language learning course and improper English grammar should not be encouraged to this degree.