What was as noteworthy as the invention of the internet has been the use of this technology to democratize, to a degree hitherto considered impossible, access to information.
(A) "What was as noteworthy as the invention of the internet"
This option is awkward and may not clearly convey the intended meaning, which is that the use of the internet to democratize access to information was as noteworthy as the invention of the internet itself.
(eliminate)
(B) "No less noteworthy than the invention of the internet"
I think we don't have any grammatical errors on this one. This option correctly conveys that the use of the internet to democratize access to information is being compared to the invention of the internet in terms of its noteworthiness. It is clear and grammatically correct.
(let's keep this)
(C) "The thing that was as noteworthy as developing the internet"
This option is awkwardly phrased. It unnecessarily introduces the word "thing," which adds no clarity or meaning. It also uses "developing" instead of "the invention of" the internet, which is incorrect IMO.
(eliminate)
(D) "Developing the internet has been none the less noteworthy than"
This option is incorrect because it changes the tense of the verb, which alters the meaning of the sentence. The present perfect tense "has been" implies that the process of developing the internet is still ongoing, which contradicts the past-tense context provided by the original sentence.
(eliminate)
(E) "Invention of the internet has been no less noteworthy as"
This option is grammatically incorrect. This also sounds un-idiomatic. The correct usage is "no less...than,".
(eliminate)
I will go with B.