I want to add to the explanations for why (D) is right and (A) is wrong because at my first try I chose (A).
I think the general idea is you should not be pretentious and just write what you actually know (as good writer would not try to express mundane ideas with difficult languages that will confuse readers.
So at a glance, it makes sense and I and some other fellow students might have gotten this question wrong with answer (A).
According to the stimulus, you shouldn't write that 'esoteric language.' What's more, we as students, mostly have been taught thus far that we shouldn't write lengthy or profuse. The more concise and the simpler, the better writing---not matter what language you use. (well, at least, in my case)
So I think, in solving this problem, this lifelong perspective on good writing principle formed sort of a lens that I see the problem through---which shouldn't repeat from this point on.
From this mistake, I learned that I shouldn't rely on or strengthen my previous knowledge or common sense by using the stimulus ahead. I shouldn't do this from this moment on---instead, we all should focus on the stimulus although it is glaring fact that we all know.
Even choosing (A), I felt something is kind of missing bx my choice was actually based on simply general understanding of the stimulus as a whole.
But if you try to analyze the small piece of stimulus, you can get plenty of support for answer (D).
The first sentence kind of holistically mention the idea that good writers shouldn't express mundane ideas with elaborate blah blah blah ,
At this point, I actually thought, 'So, what do you want to speak? So should we stop expressing mundane ideas and rather express inventive/novel ideas only?? because mundane ideas and esoteric vocabulary both sound opinionated in a sense to me.
But then it goes on, "inattentive readers may be impressed but may well misunderstand the writing'
while alert readers see through the poor writing.
==>So from this, we could get the idea that you do not try to deceive people with exaggerated language. Correct understanding is important (as opposed to misunderstanding) and pretentiousness doesn't last. give up on that. If you're going to write about something, write it as it is. Do not exaggerate. be clear. (which shouldn't necessarily be construed as 'simple'.) IDEA should correspond with STYLE.
I'm talking to myself.