Even within the same study, people responded quite differently to acupuncture, some showing increased flexibility, while others did not. (A) some showing increased flexibility, while others did not
(B) with some showing increased flexibility, while others did not
(C) with some showing an increase in flexibility and others did not
(D) some showing an increase in flexibility, while others not
(E) with some showing increased flexibility and others not

The correct answer is : option E.

Explanation:

Option (E) "with some indicating this and others not demonstrating this" forms a equal structure with 2 participles following nouns after the "with" which is a preposition.

The general rule is that there should be a verb that is being supplanted by "did". In this case, there only a participle instead of verb, so the structure would not be parallel: (A), (B), and (C) can not be correct as one can not frame the sentence like a, b, and c.  In option (D), "while others not showing" also incorrect as there would be requirement of a complete cause after while with a comma thus,  

Thus, the correct answer is : option E.

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