Read the excerpt from “Husky-The Wolf Dog of the North.”

The dog swung obediently to the right, shrewdly throwing his whole weight upon the traces. "Haw!" The manoeuvre was duplicated to the left and the sled broken out. And then, "Mush on!" (the vernacular for "get up!"). The dog whined softly, driving his claws into the frozen trail, calling every muscle into play, digging away like mad. And in answer to this tremendous exertion, the sled slowly got into motion and was dragged several lengths. Let a man try the like and marvel. Of course it was an exceptional dog, but creatures are often measured by their extremes.

This excerpt best supports a central idea in the passage by showing that

dog sled owners have their own language.
frozen ground is difficult to travel across.
huskies are obedient and tame animals.
huskies are strong and powerful animals.