The correct answer is Wikipedia. Jimmy Wales and Larry Sanger launched Wikipedia in January 2001 as a free, collaboratively edited online encyclopedia. It grew out of an earlier project called Nupedia, which used expert peer review and moved too slowly, so the two adopted wiki technology to let volunteers write and edit articles quickly, which turned Wikipedia into the massive open reference site it is today.
Wales provided the funding and vision as the entrepreneur behind the project, while Sanger, who held a philosophy background, worked out much of the early editorial policy and even coined the name Wikipedia by combining wiki and encyclopedia.
Facebook was founded by Mark Zuckerberg with fellow Harvard students. Orkut was created by Google engineer Orkut Buyukkokten and was popular in India and Brazil before shutting down later. Google itself was founded by Larry Page and Sergey Brin. None of these three match the founders named in the question, only Wikipedia does.