Final answer:
The world's largest network is the Internet, which began as a series of smaller networks that expanded and standardized into the connected online world we have today.
Step-by-step explanation:
The world's largest network is the Internet. From the SABRE system initiated by IBM in 1960 to the vision of JCR Licklider's 'Intergalactic Computer Network,' the concept of a connected world has continually evolved.
By the 1990s, the Department of Defense, in partnership with universities, helped create private networks that would ultimately become the standardized communication system we know today.
In 1982, the network of networks took shape, and by the end of the decade, the World Wide Web was conceived, heralding a new era of technology that included hypertext web pages and later multimedia content.
The answer to the question is A. Internet.