gmat_perfect wrote:Unlike frogs that metamorphose from tadpoles into adults within a one-year period, it takes three to four years for the mountain yellow-legged frog of the Sierra Nevada to reach adulthood, and so they are restricted to deeper bodies of water that do not dry up in summer or freeze solid in winter.

(A) it takes three to four years for the mountain yellow-legged frog of the Sierra Nevada to reach adulthood, and so they are - Comparison error. We are comparing frogs with it, eliminate.
(B) it takes the mountain yellow-legged frog of the Sierra Nevada three to four years until it reaches adulthood, and therefore it is - [color=red]Same as A[/color]
(C) in the Sierra Nevada, mountain yellow-legged tree frogs take three to four years to reach adulthood, thus being - being and comparison error
(D) mountain yellow-legged frogs of the Sierra Nevada take three to four years until they reach adulthood, thus - until means end. e.g sale of clothes will finish until 10.00 pm, means you know for sure that at 10.00 pm sale is going to end no matter what. Here you know for sure that frogs take 3-4 years to reach adulthood no matter what. This is kind of changing the meaning, not sure though. 'Thus' is wrong.
(E) mountain yellow-legged frogs of the Sierra Nevada take three to four years to reach adulthood, and so they are - Correct

[spoiler]OA: Later[/spoiler]