Answer : 2. "Windows NT"
Explanation :

Windows 8 is part of the Windows NT family of operating systems. Windows NT is a family of operating systems produced by Microsoft, which includes Windows NT 3.1, Windows NT 3.5, Windows NT 4.0, Windows 2000, Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1, and Windows 10. The Windows NT architecture is known for its stability, security, and advanced features, making it suitable for both personal and enterprise use.