Who sold MS-DOS to IBM?

The correct answer is Gates and Allen because they were the co-founders of Microsoft and played a pivotal role in the development and sale of MS-DOS to IBM. In the early 1980s, IBM needed an operating system for their personal computer, and they turned to Microsoft, which did not have an operating system at that time. Gates and Allen acquired an existing operating system called QDOS (Quick and Dirty Operating System) from Tim Paterson of Seattle Computer Products and then adapted it to meet IBM's requirements. This adaptation became what is known as MS-DOS (Microsoft Disk Operating System), which became a foundational software for IBM PCs and helped to popularize Microsoft's software in the personal computing market.