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  3. Scientists formerly assumed that coral populations remained stable, dead polyps being replaced by now ones that build on the "sk

Scientists formerly assumed that coral populations remained stable, dead polyps being replaced by now ones that build on the "sk

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问题     Scientists formerly assumed that coral populations remained stable, dead polyps being replaced by now ones that build on the "skeletons" left behind. Recent investigations, however, reveal more dynamic processes. Whole sections of a colony may die and not be replaced. This process, known as partial colony mortality, is evident in a series of photographs over time, but often impossible to detect in site because "skeletons" bared by the death of overlying tissue are readily overgrown by other organisms or abraded by grazers. Partial mortality can produce fission the process of a large colony splitting apart into two or more adjacent colonies that presumably have identical genetic makeup. Subsequent lateral growth may unite these colonies in a process called fusion. As a consequence of these three processes, estimates of coral ages based on size are Partial mortality and fission, which reduce colony size, occur more frequently than fusion, and thus estimates of coral age based on colony size are probably far too low.
According to the passage, all of the following are confounding factors in determining the exact age of a coral colony EXCEPT______.
选项 A、the abrading of the colony surface by feeding organisms
B、the balance between polyp births and deaths
C、partial colony death
D、reuniting of colonies after fission
答案B
解析 排除题。A、C和D文中均有提到。B是科学家们以往的认识，已经被最近的研究发现所否定。故B选项正确。
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