Answer: White Fang feels great fear for the power and hum of the city. In the next section, he will be haunted by a dream of a cable car attacking him--superimposed on his northern environment. White Fang realizes that this world is more powerful than he can fight against.
I'd say it was D or the last choice. It makes most sense to me.
Able to fix small machines and willing to let black dog go unpunished