An administrator needs to adjust the settings of an existing virtual machine.

Nutanix documentation for updating a VM through Prism Central states explicitly: “BIOS mode: You cannot modify the BIOS mode after the VM is created.” That wording directly answers the question and makes A the correct option. By contrast, vCPU count and memory allocation are common VM settings that administrators can adjust as part of lifecycle management, and boot priority can also be changed in supported conditions. The only one Nutanix calls out as restricted after creation is the BIOS mode. ( Nutanix Portal )

This reflects how foundational firmware mode is to VM identity and boot architecture. Once the VM is created using Legacy BIOS or UEFI, many guest-OS assumptions, boot-device structures, and security options depend on that original firmware model. Nutanix therefore locks this parameter after creation instead of treating it as an ordinary runtime edit. For exam preparation, this is a classic item to memorize: CPU and memory can generally be changed, but BIOS mode cannot be modified after VM creation. So the authentic Nutanix answer here is A. BIOS mode. ( Nutanix Portal )