SAT Reading & Writing · Text Structure and Purpose
Tibetan and Andean populations living at high altitude both face similarly low oxygen levels, yet researchers have found that the two…
Tibetan and Andean populations living at high altitude both face similarly low oxygen levels, yet researchers have found that the two groups show partly different patterns in their hemoglobin levels and oxygen-transport physiology. Genetic studies further indicate that different genes appear to be the primary targets of adaptation in each population, despite the shared environmental challenge both groups face.
Which choice best describes the function of the final sentence in the text?
Which choice best describes the function of the final sentence in the text?
Answer and explanation
Answer: B: It adds a genetic dimension that reinforces the passage's point about differing adaptive routes to a shared challenge.
The final sentence extends the physiological difference already described into the genetic level, adding a second, complementary layer of evidence for the same overall point: two populations solving a shared problem through different biological routes. B captures that reinforcing function. A misreads the sentence as a contradiction, when it actually supports the passage's established premise. C invents a value judgment the passage never makes. D misdescribes a closely related genetic detail as an unrelated topic shift.
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