I think he may be right. But I have not read the whole thing, so I may be wrong.
Answer:
Correct answer is A: It is a part of the exposition that describes Buck's
Explanation:
The story follows a dog named Buck, and all the misfortunes that happen to him. At one point of his life, he becomes a sled dog. It is true that in the lines following the mentioned paragraph, the author mentions that Buck welcomed these two dogs, but the accent of the story isn't really on Buck making friends. Also, there is mention about Spitz beating Billie and how Buck and Sol-leks got into a fight, but the accent of these paragraphs isn't on the fight. The writer rather focuses on the personal characteristics of each dog, which means that this is exposition that describes each of Buck's teammates.
I think informal? Family members commonly use slang :)
A.
It lets the reader know what the stakes of the story are
