TOEFL Listening: TPO-TOEFL阅读TPO - XILQDU1D42SPI142N$

According to paragraph 7, how do environments containing oxygen affect fossil preservation? A. They increase the probability that soft-tissued organisms will become fossils. B. They lead to more bacteria production. C. They slow the rate at which clay and silt are deposited. D. They reduce the chance that animal remains will be preserved.