Which of the following lines from call of the wild best supports one of the themes?
A. For the pride of the price and trail was his, and, sick unto death, he could not hear that another dog will do his work.
B. He knew he was at last answering the call, running by the side of the wood brother towards the place where he had surely came
C. As twilight fell the old bull stood with a lowered head, watching his mates- the cows he had known, the calves he had fathered, the bulls he had mastered- as they shambled on at a rapid pace through the fading light.
D. Here a yellow stream flows from rotted moose-hide sacks and sinks into the ground, with long grasses growing through it and vegetable mould overruning it and hiding its yellow from the sun; and here he muses for a time, howling once, long and mournfully, ere he departs.