TOEFL Listening: TPO-TOEFL阅读TPO - L01TXCV4N934E_W1N$

Which of the following can be inferred from paragraphs 2 and 3 about the small mammals that experience population cycles? A. Their population cycles are not affected by predators. B. Their predators' populations periodically disappear. C. They typically undergo ten-year cycles. D. They have access to places safe from predators.