Cambridge University scientists recently created nanoflowers

if, 'as to be serving' is omitted from E, will it be a better choice?

The sentence doesn't appear to have any errors in it. A distinctive feature is the semicolon, but it is used correctly to join two independent clauses. Plan to select (A), but check the choices to make sure nothing was overlooked.

A quick scan of the choices doesn't reveal any clear patterns or grouping. Two use semicolons and three use commas, but either could be correct depending on how the sentence is structured. Proceed to compare the choices more carefully.

(B) is incorrect because the proper idiomatic use of the word "instance," when indicating an example, is for instance, not "as an instance." Additionally, (B) ends up reading "be the serving as water repellents," which makes no sense.

(C) also uses the incorrect "as an instance" instead of the idiomatically correct for instance.

(D) incorrectly uses "like" to introduce an example. The word "like" is used to compare things, as in The dog's eyes were brown, like its owner's eyes. A phrase often used correctly to introduce an example is such as.

(E)'s "to be serving" is needlessly wordy and doesn't make sense following "such as." Eliminate (E).

As expected, (A) is the answer.