单选题 Government bans on the dumping of sludge anywhere in the ocean are based on the belief that the spread of sludge by ocean currents poses a danger to people. Since it is not clear that sludge dumped on the ocean bottom, far from coasts, would endanger people, the bans should be revised to apply only to coastal waters.
Each of the following, if true, supports the conclusion that the bans on ocean dumping should be revised EXCEPT:

A、 The slow-moving water near the ocean bottom mixes so slowly with water closer to the surface that sludge dumped on the ocean bottom would be decomposed by bacteria before currents could bring it to the surface.
B、 Many locations on the ocean bottom far from coasts are geologically stable, and unlikely to be disrupted by earthquakes or volcanic eruptions.
C、 Deep-sea marine plants and animals in the human food chain live at depths far above the ocean bottom.
D、 Dumping large amounts of sludge would have an unknown effect on organisms that live on the ocean bottom.
E、 (E) The technology exists to lower sewage sludge to oceanbottom dump sites without contaminating waters closer to the surface.

【正确答案】 D

【答案解析】