Answer:
The BEST option to accomplish the upgrade to Windows 10 Enterprise with minimal user downtime would be to configure a provisioning package and have each user apply it to their machine.
This option allows users to upgrade their devices to Windows 10 Enterprise at their convenience, without having to bring their device to IT for backup and restore. It also minimizes downtime since users can apply the provisioning package during off-hours or at a time that is convenient for them.
Additionally, using a provisioning package ensures that the upgrade process is standardized and consistent across all devices, which can help avoid potential issues that may arise from performing individual in-place upgrades or having users upgrade their devices independently.
Overall, this option offers the most flexibility and minimal disruption to the users while ensuring a consistent and efficient upgrade process for the network administrator.