Read the two excerpts from The Call of the Wild describing the wolf.

The wolf whirled about, pivoting on his hind legs after the fashion of Joe and of all cornered husky dogs, snarling and bristling, clipping his teeth together in a continuous and rapid succession of snaps.

***

For the better part of an hour the wild brother ran by his side, whining softly.

How has the wolf changed?

He has become anxious about his pack.
He has become friendlier toward Buck.
He has become timid because of the sounds.
He has become stronger in his demeanor.

The wolf has become stronger in his demeanor.

Based on the given excerpts, it can be inferred that the wolf has become stronger in his demeanor. In the first excerpt, the wolf is described as snarling, bristling, and snapping his teeth in a continuous and rapid succession. This behavior shows a more aggressive and assertive nature, suggesting that the wolf has become stronger. Therefore, the correct answer is: He has become stronger in his demeanor.