Off late, the interest in nano systems is increasing due to their

GMATNinja KarishmaB could you please help here.

I believe OA should be D here and not C. In C we have a comma in between just two list elements. Isn't that sufficient grounds to eliminate C?

Element 1: micro surgeries
Element 2: operations in minute or critical micro environments

Shouldn't these two elements be seperated just by and? A comma + and indicates start of the second independent clause and "operations in minute or critical micro environments" is not an independent clause since it lacks a verb.

Please correct if I'm going wrong with this line of thinking. Also, I can't seem to find any mistakes in D. It appears to have perfect parallelism.

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GMATNinja sayantanc2k IanStewart MartyTargetTestPrep

Can you please help with your expert solution to this question? I am not satisfied with the OA and OE.

Couldn't it be that in option A there are 2 items in the list: micro surgeries and minute operations? And the part "operating in critical micro environment" is the modifier of micro surgeries. That makes option A totally correct.

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While, a phrase such as "operating in micro environments" could in theory be an appositive modifying a preceding noun phrase, such as "micro surgeries," since "micro surgeries" is a plural thing, whereas "operating in micro environments" is a singular action, that modification does not make sense.

Meanwhile, "micro surgeries, operating in critical micro environments, and minute operations" combines two different types of ideas in one list. "Surgeries" and "operations" are types of events whereas "operating" is an action. So, the list in the (A) version, while almost correct, is a little off.

That said, there's no clear reason that anyone with ordinary knowledge would have why the list in (C) is any better than the list in (D). So, both (C) and (D) are viable correct answers, and this question needs some tuning.

I agree with you that A can be correct, if you interpret "operating in micro-environments" as a definitional phrase. It's perfectly fine to say something like "Somnambulism, walking in one's sleep, is a condition that can be brought on by stress." Here, "walking in one's sleep" defines what "somnambulism" means, and is not an item in a list. You can read answer A in the same way, where "operating in micro-environments" serves to define what the technical term "microsurgeries" means.

The standard of writing in this question is so poor though that it's hard to tell what any of it is trying to say, which makes it impossible to choose a good answer. For one thing, there's no way to tell if "minute operations" is a term of art that needs to be preserved, or if we can freely reword it to say "operations in minute micro-environments" as the OA does. And the phrase "minute micro-environment" in the OA is simply absurd; of course a "micro-environment" is "minute", because "micro" and "minute" mean the same thing. In an official question, I'd rule out C on that basis alone. It's always best to stick to official problems, because then you can be sure you'll be learning things relevant on the real test (and to clear and precise writing generally).

Thank you so much MartyTargetTestPrep and IanStewart .. This helps a lot!

You are right that with two elements in the list, we do not use the oxford comma. In any case, do not worry too much about the question - all elements of the list seem to be the same to the non-medico eye.