According to paragraph 2, what suggests that human activity played a role in the extinction of mammals about 11,000 years ago? A. Climate changes that would have favored human population expansion occurred at the time of the extinctions. B. The presence of human hunters had caused animal extinctions in other time periods. C. There was a pattern of climate change earlier than 11,000 years ago that had not caused animal extinctions. D. Harmful climate changes 11,000 years ago would have required humans to hunt larger numbers of animals for food.