Which type of virtual machine migration involves stopping the machine during the process?

Cold migration is the correct choice because it refers to the process of migrating a virtual machine while it is turned off. This type of migration requires the virtual machine to be completely powered down, meaning that its operational state and data are not actively in use during the transfer. As a result, the entire contents of the VM, including its virtual disks and configuration settings, are moved to the new environment without any live data or processes being affected. This ensures that the integrity of the data is maintained throughout the migration process, albeit at the cost of downtime.

In contrast, live migration and hot migration allow for the virtual machine to remain operational during the migration, which can be advantageous for minimizing service interruptions but does not apply to this question. Incremental migration generally refers to transferring only the changes made since the last backup or migration, rather than the entire machine. Therefore, the key characteristic of cold migration is its requirement for the virtual machine to be stopped during the migration process, which distinguishes it clearly from the other options.