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题库 / Prep2012-CR-34
In polluted environments, dolphins gradually accumulate toxins in their body fat, and the larger the dolphin the more accumulated toxins 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.
Dolphins, other marine mammals, have a higher proportion of body fat than do most land mammals.
环境污染→ 海豚妈妈的母乳有毒 →小海豚dolphin calves死亡率高
增强？
选项A（√）
The 【survival rate存活率】 of 【firstborn dolphin calves小海豚】 in the area along Florida's Gulf Coast is 【highest 最高】for those whose 【mothers were killed before they were weaned 海豚妈妈在断奶前被杀】.
在佛罗里达州墨西哥湾沿岸地区，那些海豚妈妈在断奶前被杀的海豚幼崽的存活率最高。
= 海豚妈妈死了→ 小海豚还没喝够海豚妈妈的毒奶 → 小海豚体内累积的毒素不够多→ 小海豚还没达到死的标准（所以存活下来）
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