Which of the following is not a Windows version?

مندرجہ ذیل میں سے کون سا ونڈوز ورژن نہیں ہے؟

Windows 9

Windows 7

Windows 10

None of these

Windows XP, Windows 7, Windows 8 and Windows 10 are the windows operating system versions.
Windows 9 never released.
Microsoft company released Windows 10 OS directly after Windows 8 OS.