What was the first version of Windows to incorporate the Aero Glass theme?

What was the first version of Windows to incorporate the Aero Glass theme?

• Windows Vista
• Windows 8
• Windows XP
• Windows 7 

EXPLANATION

Windows Aero (a backronym for Authentic, Energetic, Reflective, and Open)^[1] is a design language introduced in the Windows Vista operating system. The changes made in the Aero interface affected many elements of the Windows interface, including the incorporation of a new look, along with changes in interface guidelines reflecting appearance, layout, and the phrasing and tone of instructions and other text in applications.
Windows Aero was in force during the development of Windows Vista and Windows 7. In 2012, with the development of Windows 8 and Windows Server 2012, Microsoft moved on to a design language codenamed "Metro".

On Windows Vista and Windows 7 computers that meet certain hardware and software requirements, the Aero Glass theme is used by default, primarily incorporating various animation and transparency effects into the desktop using hardware acceleration and the Desktop Window Manager (DWM). In the "Personalize" section added to Control Panel of Windows Vista, users can customize the "glass" effects to either be opaque or transparent, and change the color it is tinted. Enabling Aero Glass also enables other new features, including an enhanced Alt-Tab menu and taskbar thumbnails with live previews of windows, and "Flip 3D", a window switching mechanism which cascades windows with a 3D effect.
Windows 7 features refinements in Aero Glass, including larger window buttons by default (minimize, maximize, close and query), revised taskbar thumbnails, the ability to manipulate windows by dragging them to the top or sides of the screen (to the side to make it fill half the screen, and to the top to maximize), the ability to hide all windows by hovering the Show Desktop button on the taskbar, and the ability to minimize all other windows by shaking one.
Use of DWM, and by extension the Aero Glass theme, requires a video card with 128 MB of graphics memory (or at least 64 MB of video RAM and 1 GB of system RAM for on-board graphics) supporting pixel shader 2.0, and with WDDM-compatible drivers. Aero Glass is also not available in Windows 7 Starter, only available to a limited extent on Windows Vista Home Basic, and is automatically disabled if a user is detected to be running a non-genuine copy of Windows.^[16][17] Windows Server 2008 and Windows Server 2008 R2 also support Aero Glass as part of the "Desktop Experience" component, which is disabled by default.^[18]