Read the sentence from The Call of the Wild. 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.

Which choice best describes the effect of the underlined phrases in this excerpt?

A They highlight the wolf's confusion about Buck's species. They highlight the wolf's confusion about Buck's species.

B They highlight the wolf's anger toward tamed animals. They highlight the wolf's anger toward tamed animals.

C They emphasize the wolf's need to defend its territory. They emphasize the wolf's need to defend its territory.

D They emphasize the wolf's aggression toward Buck. They emphasize the wolf's aggression toward Buck.