Scientists hypothesize that Tyrannosaurus Rex was a predator so overwh

I think option b changes the meaning. I am in dilemma whether to choose A or B.
Please advise.

OE :

The underlined portion of the sentence contains prepositional phrases, so check for misplaced modifier errors. Because the pair of prepositional phrases at the time of its extinction is closest to the noun superior, that phrase incorrectly modifies superior rather than Tyrannosaurus rex, which is a misplaced modifier error. Eliminate A and look for obvious repeaters. Because the prepositional phrases at the time of its extinction appear at the end of choices D and E, they are obvious repeaters. Eliminate D and E. Now evaluate the remaining answer choices individually looking for reasons to eliminate each.

Choice B fixes the original misplaced modifier error by moving the phrase at the time of its extinction close to Tyrannosaurus rex and introduces no new errors, so keep choice B. Choice C fixes the misplaced modifier error but introduces an idiom error by using so without utilizing the correct idiom so…that. Eliminate C.