But the only sentences stating that specific versions have actually received C2 type certifications are in the summary. And the statement there is that 3.5 was certified as of 1995 in the USA, and 3.5.1 was given a E3/F-C2 rating in the UK. Nowhere in that article does it say that any version of 4.0 ever received C2 certification.
If you think I'm missing something, please quote directly from the relevant section of the article.
"SAIC's Center for Information Security Technology, an authorized TTAP Evaluation Facility, has performed the evaluation of Microsoft's claim that the security features and assurances provided by Windows NT 4.0 with Service Pack 6a and the C2 Update with networking meet the C2 requirements of the Department of Defense Trusted Computer System Evaluation Criteria (TCSEC) dated December 1985." 
Anyway isn't all of this missing the point that the TCSEC C* requirements didn't really amount to much anyway? It's a pity no general purpose operating systems were ever evaluated to A1 criteria, and that that the Common Criteria haven't lead to systems like EROS/Coyotos/Capros receiving more development attention.