TOEFL Reading: ETS-TOEFL阅读机经 - 3RQ6EPISK94W6S17L$

In paragraph 3, why does the author include the information that wolves and lions "had hunted giant bison for tens of thousands of years" A. To emphasize how good the bison's defenses were B. To support the claim that only wolves and lions hunted the bison for long enough to cause changes in its evolution C. To help explain why predation by wolves and lions cannot account for the changes that occurred in bison twelve thousand years ago D. To introduce a discussion of how changes in bison directly affected other large animals in North America