Correct Answer: A
Explanation:
The missing word is describing some aspect of the answer which is present despite the time taken to arrive at the solution. C is grossly incorrect as placing it in the blank will render the sentence meaningless. Out of the remaining options, ‘loopholes’ and ‘ambiguity’ are the only two words that carry the same meaning and they complete the intended meaning of the sentence. Therefore, A and D are the correct answers.