TOEFL Reading: ETS-TOEFL阅读机经 - 7Y5Z6ZM84H3JK56TL$

Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information. A. However, soils that are unable to absorb much water experience massive runoff during heavy rains. B. However, where neither protective vegetation nor mulch covers the soil, much rainwater can be lost to runoff. C. However, on extremely steep slopes there is no vegetative cover or mulch to prevent runoff. D. However, in more extreme conditions water that runs off can carry away the vegetative cover and the surface mulch