Which of these is a mobile operating system?

Android is better than iOs, IMHO.

Windows can be a mobile OS too. Relatively recently - Windows Phone which was running on Lumia phones. These were made by Nokia, but later by the MS and branded Microsoft. Windows Mobile was older platform, running on PDA devices for example.

Why did the Android phone bring a ladder to the Apple store? To reach the iCloud and prove it’s got higher standards!

windows phone is a thing although it is extinced

Technically both Android and Windows are valid, although Windows Mobile was discontinued.

Nor a fan of that system.

Maybe too easy...