Which sentence is not correct?

• A. 
  “hypertext” means “a way of joining a word or image to another page, document, etc. on the Internet or in another computer program so that you can move from one to the other easily”
• B. 
  Berners-Lee had begun working with hypertext in the early 1980s.
• C. 
  An early prototype implementation of the Web became operational at CERN in 1989.
• D. 
  The idea slowly spread to universities in the rest of the world.