MS-DOS developed in

MS-DOS, which stands for Microsoft Disk Operating System, was developed by Microsoft and released in 1984. It was a command-line operating system that provided a foundation for subsequent versions of Microsoft Windows operating systems. MS-DOS was designed to be used with IBM PC compatible hardware, becoming a key component in the widespread adoption of personal computers in the 1980s and early 1990s.

Therefore, the correct answer is Option B: 1984.