SAT Reading & Writing · Text Structure and Purpose
Genomic studies have revealed a complex history of gene flow between polar bears and brown bears, with some present-day brown bear…
Genomic studies have revealed a complex history of gene flow between polar bears and brown bears, with some present-day brown bear populations retaining genetic ancestry from ancient polar bears, and some polar bear populations retaining ancestry from ancient brown bears. This bidirectional pattern complicates any simple family-tree picture in which the two species diverged cleanly from a single common ancestor and then evolved in complete isolation from one another.
Which choice best states the main purpose of the text?
Which choice best states the main purpose of the text?
Answer and explanation
Answer: B: To describe a genetic finding that complicates a simple model of clean, one-directional species divergence
The passage explicitly names what the finding complicates, a "simple family-tree picture" of clean divergence and total isolation, and frames the bidirectional gene flow as the reason that simple picture doesn't hold. B captures that purpose directly. A overstates the finding into a claim about species identity the passage doesn't make. C reverses the passage's actual point, which describes bidirectional ancestry, not one species evolving from the modern form of the other. D invents a methodological criticism the passage never raises.
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