The correct answer is D. The Internet was first implemented in the 1980s.
The 1940s were a time of great technological advancement, with the development of radar, the atomic bomb, and the jet engine. However, the Internet was not yet a reality.
The 1950s saw the development of the first computers, but they were large and expensive, and were not connected to each other.
The 1960s saw the development of the ARPANET, which was a network of computers that was used by the US military. The ARPANET is considered to be the precursor to the Internet.
The 1970s saw the development of the first email system, and the first online chat system. However, the Internet was still not widely available to the public.
The 1980s saw the development of the World Wide Web, which made it possible for people to access information on the Internet using a graphical user interface. The World Wide Web is what made the Internet accessible to the general public.
Therefore, the correct answer is D. The Internet was first implemented in the 1980s.