A student asked me for an explanation of this one, so I'm posting it here to serve everyone.
His question: "This is the type of question that gives me the most trouble. No other tips to look for, just one issue to solve. Any tips on how to approach such question?"
Here's my response:
We have to find the decision point. “Instead of” and “as opposed to” are 99% interchangeable, so there is no way to choose one over the other, and therefore neither of them could be the answer.
So there must be something else we need here, not just the logical opposition. And it turns out this is a
structural parallelism issue! You could think of this as an X and Y parallelism question, like Correlative Constructions (not only X but also Y, where X and Y must be parallel). OK, so what are we comparing?
(Think about this for yourself before you read on - you may see it)
We are comparing the two places that bonding happens :
X: over a broad surface
Y: a series of regularly spaced points …
Are X and Y parallel? Not really. In Y, we need a word like “over” - a preposition.
You can hear it clearly if you read this as two different sentences:
Bonding happens over a broad surface ✅
Bonding happens a series of regularly spaced points 👎
We need the “at” proposed in D and E. And E is a wordy mess, so D is our winner.
This is definitely tough, because they aren't the SAME preposition. But looking at it from a structural perspective shows us what is missing.
Hope this helps! Let me know.