What kind of external conflict is reflected in this excerpt from jack london’s the call of the wild?

from then on, it was a war between them. spitz, as lead-dog and acknowledged master of the team, felt his supremacy threatened by this strange southland dog. and strange buck was to him, for of the many southland dogs he had known, not one had shown up worthily in camp and on trail. they were all too soft, dying under the toil, the frost, and starvation. buck was the exception. he alone endured and prospered, matching the husky in strength, savagery, and cunning. then he was a masterful dog, and what made him dangerous was the fact that the club of the man in the red sweater had knocked all blind pluck and rashness out of his desire for mastery. he was preeminently cunning and could bide his time with a patience that was nothing less than primitive.

a. the external conflict of character versus character
b. the internal conflict of character versus self
c. the external conflict of character versus nature
d. the external conflict of character versus society