Agree, it's easy to narrow down to choices A & C, but then there is no basis to prefer "Most likely" over "likely".
A quick search I found this question from Economist GMAT Blog Post, and here is the reason, which I don't agree, to eliminate choiceC:
Notice how answer option C changes the meaning of the original sentence. 'Likely' is not the same as 'most likely'. So, you can eliminate C.
IMO, as long as the sentence is logical, correct, clear and concise, it is fine.
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A quick search I found this question from Economist GMAT Blog Post, and here is the reason, which I don't agree, to eliminate choiceC:
Quote:
Notice how answer option C changes the meaning of the original sentence. 'Likely' is not the same as 'most likely'. So, you can eliminate C.
IMO, as long as the sentence is logical, correct, clear and concise, it is fine.
...
