Which of the following is the BEST way to secure a workstation which is shared by multiple users using the same guest account?

Strong password requirements are ineffective when all users share the same account because enforcing a complex password still means all users know it, and it does not limit what those users can do once logged in.

A password-protected screensaver would lock the workstation during inactivity but does not prevent users from accessing the system using the known shared credentials.

Restricting the guest account's privileges directly limits what any user of that shared account can do - such as preventing software installation, access to sensitive system areas, or modification of system settings. Since all users share the same credentials, privilege restriction is the only control that applies uniformly to every session, making it the most impactful security measure available.

Renaming the guest account provides minimal security through obscurity and does nothing to limit what users of that account can access or change.