{D} "two people" is wrong.. it should have been "person" ... "people" is plural .. Also, "the labelling of them" is awkward.

{E}

Labeling of is redundant. If we are unable to check whether two people or two persons in order to eliminate the answer choice D.

Hi ProGMAT,

D features a few problems. The author aims to highlight a comparison between people's and snowflakes' diversity.

D) that no two snowflakes, just like no two people, are similar enough to justify the labeling of them

1. Just like is a comparison signal; the comparison is alright (both parallel and logical). Since there are better options, I find "just like no two people" redundant, but this is just a scrupulous caveat.
2. Word "people" is plural in meaning, however it can be singular in both writing and meaning when referring to "nation" or "race"; In such a circumstance the plural of "people" is "peoples", for instance "the peoples of Europe are working together to create a green environment".
3.Another big issue in this sentence is "the labeling of them" such expression to make sense needs an "as". Thus "the labeling of them as", would have been correct.

E) is by far the best option.

hope it helps,
-tathastuGMAT