To which of the following versions and editions of Windows 7 can you directly upgrade a computer running Windows Vista Enterprise (x86)?

A.
Windows 7 Home Professional (x86)

B.
Windows 7 Ultimate (x86)

C.
Windows 7 Ultimate (x64)

D.
Windows 7 Enterprise (x64)

Explanation:
The only applicable solution is Windows 7 Enterprise (64-bit) as for the following reasons:

All versions are support Hardware wise.
Requirements:
Windows 7 Home Premium, Professional, Ultimate, and Enterprise editions have the following minimum hardware requirements:
* 1 GHz 32-bit (x86) or 64-bit (x64) processor
* 1 GB of system memory
* a 40 GB hard disk drive (traditional or SSD) with at least 15 GB of available space
* a graphics adapter that supports DirectX 9 graphics, has a Windows Display Driver Model (WDDM) driver, Pixel Shader 2.0 hardware, and 32 bits per pixel and a minimum of 128 MB graphics memory

XP Mode
Windows XP Mode is a downloadable compatibility option that is available for the Professional, Enterprise, and Ultimate editions of Windows 7. Windows XP Mode uses the latest version of Microsoft Virtual PC to allow you to run an installation of Windows XP virtually under Windows 7.

Use all of the installed memory
The x86 version supports a maximum of 4 GB of RAM, whereas the x64 version supports a maximum of 8 GB of RAM.

Windows 7 Professional
Windows 7 Professional is available from retailers and on new computers installed by manufacturers. It supports all the features available in Windows Home Premium, but you can join computers with this operating system installed to a domain. It supports EFS and Remote Desktop Host but does not support enterprise features such as AppLocker, DirectAccess, BitLocker, and BranchCache.

Windows 7 Enterprise and Ultimate Editions
The Windows 7 Enterprise and Ultimate editions are identical except for the fact that Windows 7 Enterprise is available only to Microsofts volume licensing customers, and Windows 7 Ultimate is available from retailers and on new computers installed by manufacturers. The Enterprise and Ultimate editions support all the features available in other Windows 7 editions but also support all the enterprise features such as EFS, Remote Desktop Host, AppLocker, DirectAccess, BitLocker, BranchCache, and Boot from VHD.