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In polluted
environments, dolphins gradually accumulated toxins in their body fat, and the
larger the dolphin the more accumulated toxin it can tolerate. Nearly 80 percent of the toxins a female
dolphin has accumulated pass into the fat-rich milk her nursing calf
ingests. Therefore, the unusually high
mortality rate among dolphin calves in the industrially contaminated waters
along Florida’s Gulf
Coast is probably the result of their being poisoned by their
mother’s milk.
Which of the following, if
true, most strengthens the argument?
- The survival
rate of firstborn dolphin calves in the area along Florida’s Gulf
Coast is highest for those whose mothers were killed before
they were weaned.
- The rate at
which adult dolphins living in the waters along Florida’s Gulf
Coast accumulate toxins is no higher than that of adult
dolphins in comparably polluted waters elsewhere.
- Among dolphin
calves born in the area along Florida’s Gulf
Coast, the mortality rate is highest among those with living
siblings.
- As dolphins age,
they accumulate toxins from the environment more slowly than when they were
young.
E.
Dolphins, like other marine mammals, have a higher proportion of body fat than
do most land mammals.
答案是A, 可是我一点思路也没有,谁能帮我解释一下A选项,并给一个推理关系呀
先谢
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