Sentence Correction (SC) | Re: Students in the metropolitan school district lack math skills to such

I have a question: Do people know just by looking at choice A that it is testing the "so X that Y" idiom?
Many explanations in the thread mention that as a reason for elimination of choice A. Are people able to identify based on the use case (wherein the sentence wants to highlight extent of something and they expect only this particular idiom to be used and no other? ) or only after looking at all answer choices could they identify the idiom tested? Just wanted to understand the mindset
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