In paragraph 5, why does the author discuss what happened in Australia 40,000 years ago A. To suggest that humans most likely arrived in North and South America much earlier than 11,000 years ago B. To make a comparison that supports the prehistoric overkill hypothesis C. To argue that most extinctions can be traced to the impact of humans on the environment D. To emphasize the similarities between the extinctions that occurred in Australia and those that occurred in Africa and Europe