The Microsoft 365 E5 subscription includes a license for Windows 10/11 Enterprise. The Subscription Activation feature is designed specifically for this scenario. It allows a device with a valid Windows 10 Pro license to be seamlessly upgraded to Windows 10 Enterprise when a user with a qualifying subscription (like Microsoft 365 E5) signs in with their Azure AD credentials. This process is automatic, requires no product keys or reboots, and is the most efficient method for an edition step-up upgrade, thus minimizing administrative effort.

A. Windows Autopilot is primarily for provisioning new devices or resetting existing ones to a known good state, not for performing an edition upgrade on already deployed and configured devices.
B. A Microsoft Deployment Toolkit (MDT) deployment requires significant infrastructure setup, including creating deployment shares and task sequences, which is contrary to the requirement of minimizing administrative effort.
D. An in-place upgrade using installation media would require distributing the media and running the setup on each of the 100 devices, a process that is far more labor-intensive than Subscription Activation.

1. Microsoft Learn. (2023). Windows Subscription Activation. "Subscription Activation for Windows is a deployment method that enables you to change the SKU from Pro to Enterprise with no keys and no reboots... When a licensed user signs in to a device

Windows changes from Pro to Enterprise." Retrieved from https://learn.microsoft.com/en-us/windows/deployment/windows-subscription-activation

Section: "How it works".

2. Microsoft Learn. (2023). Prerequisites for Windows Subscription Activation. "A supported version of Windows Pro edition... A device that is Microsoft Entra joined

or hybrid joined... A Microsoft 365 E3/E5 or an Enterprise Mobility + Security E3/E5 or other qualifying subscription that includes a license for Windows Enterprise." Retrieved from https://learn.microsoft.com/en-us/windows/deployment/windows-subscription-activation

Section: "Prerequisites".

3. Microsoft Learn. (2023). Windows Autopilot overview. "Windows Autopilot is a collection of technologies used to set up and pre-configure new devices

getting them ready for productive use. You can also use Windows Autopilot to reset

repurpose and recover devices." Retrieved from https://learn.microsoft.com/en-us/mem/autopilot/windows-autopilot

Section: "Overview".