Which action should an administrator perform to ensure they can revert a virtual machine to its previous state after an OS update?

Taking a snapshot of a virtual machine (VM) is the appropriate action to ensure that the administrator can revert the VM to its previous state after an operating system update. A snapshot captures the current state of the VM, including the virtual machine's disk, memory, and settings. This allows the administrator to create a recovery point before applying changes or updates.

If issues arise after the OS update, the administrator can quickly revert back to the point where the snapshot was taken, restoring the VM to its exact state at that moment. This capability is a vital feature of virtualization platforms, providing an efficient and effective way to manage changes and maintain system stability.

In contrast, cloning a VM to a template or another virtual machine creates a new instance rather than preserving the current state, making it less suitable for reverting changes after an update. Migration is used primarily for relocating the VM rather than managing its state, thus not serving the purpose of reverting to a previous configuration effectively.