Genetic research suggests that after cheetah ancestors had migrated fr
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26 Oct 2021, 14:01
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 the ice ages that have wiped out its
==> the species (is) safe from the (ice ages) that (have wiped)----does ice age still exists? Is it still wiping out the species' populations(use of perfect tense)? I don't think so. Out goes A.
B. migrated from North America to Asia more than 100,000 years ago, when sea levels are thought to have been much lower, they quickly spread to Africa, where the species was safe from the ice ages that wiped out its
==> bad issues from A is not present in B. However, the phrase "when see levels are thought" is little funny. Why use present tense here? But as sea levels of 100,000 years ago are thought today lets hold on to B for a moment.
C. had migrated from North America to Asia more than 100,000 years ago, when sea levels are thought to have been much lower, they quickly spread to Africa, where the species was safe from the ice ages that wiped out their
==> wiped out (their). Here, their don't have antecedent. Species is singular noun here. So, C out
D. migrated from North America to Asia more than 100,000 years ago, when sea levels are thought to be much lower, they quickly spread to Africa, where the species has been safe from the ice ages that wiped out its
==> where the species (has been) safe from ice ages------present perfect means the species was safe and still now safe from the ice ages. But ice ages don't exists anymore. So, D out
E. 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 wiped out their
==> same problems as A and D are present here. E is out too.
that leaves us with the only option B. So, B is the right answer.