Prep2012-Pack1-CR-034 VCR001296 Medium
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?
A. 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.
B. 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.
C. Among dolphin calves born in the area along Florida's Gulf Coast, the mortality rate is highest among those with living siblings.
D. As dolphins age, they accumulate toxins from the environment more slowly than when they were young.
E. Dolphins, other marine mammals, have a higher proportion of body fat than do most land mammals.
Prep2012-Pack1-CR-035 VCR001345 Medium
Perkins: According to an article I read, the woolly mammoth‘s extinction in North America coincided with a migration of humans onto the continent 12,000 years ago, and stone spearheads from this period indicate that these people were hunters. But the author's contention that being hunted by humans contributed to the woolly mammoth‘s extinction is surely wrong since, as paleontologists know, no spearheads have ever been found among the many mammoth bones that have been unearthed.
Which of the following, if true, provides the strongest reason for discounting the evidence Perkins cites in arguing against the contention that being hunted by humans contributed to the North American extinction of woolly mammoths?
A. At sites where mammoth bones dating from 12,000 years ago have been unearthed, bones of other mammals have rarely been found.
B. The stone from which stone spearheads were made is unlikely to have disintegrated over the course of 12,000 years.
C. Conditions in North America 12,000 years ago were such that humans could not have survived there on a diet that did not include substantial amounts of meat.
D. Cave paintings in North America that date from 12,000 years ago depict woolly mammoths as well as a variety of other animals, including deer and buffalo.
E. Because of the great effort that would have been required to produce each stone spearhead, hunters would have been to leave them behind.
