Which is the oldest version of Windows in this list?

Which is the oldest version of Windows in this list?

• Windows NT 3.1
• Windows XP
• Windows ME
• Windows 98 

EXPLANATION

In May 1990, Microsoft released Windows 3.0, a new version of its MS-DOS-based Windows desktop environment. Windows 3.0 sold well, and the resulting shift in Microsoft's marketing strategy eroded their partnership with IBM—who wanted Microsoft to concentrate solely on developing OS/2 as its primary platform as opposed to building their future business around Windows.^[20] Users and developers were unsure of whether to adopt Windows or OS/2 due to these uncertainties (a situation magnified by the fact that the operating systems were incompatible with each other at the API level), while Microsoft's resources were also being drained by the simultaneous development of multiple operating systems.^[21][22]
In August 1990, as a response to the popularity of Windows 3.0, the NT OS/2 team decided to re-work the operating system to use an extended 32-bit port of the Windows API known as Win32. Win32 maintained the familiar structure of the 16-bit APIs used by Windows, which would allow developers to easily adapt their software for the new platform while maintaining a level of compatibility with existing software for Windows.^[23] With the shift to a Windows-like architecture, the operating system's shell was also changed from OS/2's Presentation Manager to Windows' Program Manager.^[24][25][26]
Due to these changes, NT was not presented at COMDEX 1990 as was originally planned.^[24] Neither the general public nor IBM knew about the transformation of NT OS/2 into Windows NT at the time.^[27] Although the companies did agree to a revised partnership where IBM and Microsoft would alternate developing major versions of OS/2 instead of collaborating on each version,^[28] IBM eventually learned of Microsoft's Windows NT plans in January 1991, and immediately ended the OS/2 partnership. IBM would solely develop OS/2 2.0 (as was planned under the amended version) and all future versions, without any further involvement from Microsoft.^[23][29]
In October 1991, Windows NT received its first public demonstration at COMDEX. In an effort to ensure software taking advantage of Windows NT was available upon its release (scheduled for late-1992), Microsoft also distributed a 32-bit software development kit to selected developers in attendance.^[30][31] The demonstration was positively received; PC Magazine called Windows NT "the modern reinvention of the operating system", but at the same time claimed that it was unlikely that the promised backward compatibility would be kept for the final release.^[32][33] In March 1992, Microsoft also released Win32s, which would allow Windows 3.1 to have partial compatibility with Windows NT programs for the purposes of developing software optimized for the platform.^[34]
At Microsoft's Win32 Professional Developers Conference in June 1992, Windows NT was demonstrated running on x86 and MIPS processors, while a beta version of Windows NT and an updated development kit were also made available.^[35] Concurrently, Microsoft announced a new version of its SQL Server product for Windows NT; Unix vendors feared that the software could be a killer app that would affect the market share of Unix systems.^[36][37] Concerns were also raised over NT's memory usage; while most computers of the era shipped with 4 megabytes of RAM, 16 MB was recommended for NTs. Due to the high cost of RAM at the time, critics thought that its high system requirements could affect the sales and adoption of Windows NT. Steps were taken to reduce its memory usage through methods such as paging.^{[38][39][40][41]}
Microsoft began releasing public beta builds of NT in October 1992, and a month later at COMDEX, a presentation focusing on third-party software for Windows NT was held.^[42][43][44] The final pre-release version of NT was released in March 1993, alongside the unveiling of the server version, Windows NT with LAN Manager. Although its stability and performance had improved, there were still fears that the OS could be released in an unfinished state or delayed further into 1993.^[45][46]