GMAT Sentence Correction (SC) | Genetic research suggests that after cheetah ancestors had migrated fr

Genetic research suggests that after cheetah ancestors had migrated from North America to Asia more than 100,000 years ago, when sea levels were thought to have been much lower, they quickly spread to Africa, where the species is safe from the ice ages that have wiped out its populations on other continents.

A.had migrated from North America to Asia more than 100,000 years ago, when sea levels were thought to have been much lower, they quickly spread to Africa, where the species is safe from
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