The correct answer is option 'C', Windows 7 Maximum, which is not a version of Windows 7. The available versions of Windows 7 are Windows 7 Ultimate, Windows 7 Professional, and Windows 7 Home Premium.

Explanation:
- Windows 7 Ultimate: This is the most comprehensive and feature-rich version of Windows 7. It includes all the features and functionalities available in the other versions, such as Home Premium and Professional, as well as additional features like BitLocker encryption, multiple language support, and more. Windows 7 Ultimate is designed for users who require advanced features and flexibility.

- Windows 7 Professional: This version of Windows 7 is targeted towards small business owners and professionals. It includes features like domain join, remote desktop hosting, and advanced network backup options. Windows 7 Professional is suitable for users who need to connect to corporate networks and manage their devices in a business environment.

- Windows 7 Home Premium: This version of Windows 7 is designed for home users and provides a balance between features and affordability. It includes features such as Windows Media Center for media playback and recording, improved Windows Aero desktop experience, and support for home networks. Windows 7 Home Premium is suitable for most home users who do not require advanced business or enterprise features.

- Windows 7 Maximum: There is no version of Windows 7 called "Windows 7 Maximum." This option is incorrect and does not exist.

In summary, Windows 7 Maximum is not a valid version of Windows 7. The correct versions of Windows 7 are Windows 7 Ultimate, Windows 7 Professional, and Windows 7 Home Premium.