Final answer:
The Windows Update policy that prevents automatic restarting when a user is logged on during scheduled updates.
Step-by-step explanation:
The Windows Update policy that will allow WSUS clients to restart outside of active hours when an update requires a restart is the "No auto-restart with logged on users for scheduled automatic updates installations" policy.
This policy prevents the computer from automatically restarting if a user is logged on when the update installation is scheduled.