I would say the correct answer is B. primitive man.
The point of the entire novel is that Buck is fighting his urges to go to the wilderness and succumb to his wild identity of a wolf. Thus, dreaming about the primitive man clearly portrays his struggle between his two identities, that of a domesticated dog and that of a wild wolf.
THE ANSWER IS B, SECOND CHOICE
1. having my favorite show canceled is minor
2. getting a haircut is major
3. gaining a new best friend is minor
4. repainting my room is major
5. going to a new school is major
6. moving far away is major
