Bunuel
Panama seceded from Colombia in 1903, except for Panama constructing a canal, the two countries continued on similar courses for the next decade.
A. except for Panama constructing a canal
B. except in constructing Panama's canal
C. but other than in Panama's construction of a canal
D. but other than the construction of a canal in Panama
E. but other than in constructing the Panama canal
Official Explanation
Creating a filter: as we cut our way through the original sentence, we can see that it's not actually grammatically a sentence. There are two independent clauses without a conjunction joining them. We'll look for this error in the other answer choices.
Applying the filter: choice (B) has the same problem. Choice (D) sets up an illogical comparison between "construction" in the answer choice and "countries" after the answer choice. Choices (C) and (E) are similar to each other. Their main difference is in the meaning conveyed; (C) conveys that Panama constructed the canal without Colombia, and (E) conveys that the two countries constructed it together. The sentence says that these two countries otherwise continued on similar courses, as indicated by the words "but other than." That means they didn't continue on similar courses with respect to the canal. Choice (E), therefore, doesn't fit the logic of the sentence.
The correct answer is (C).