Which command installs GRUB 2 into the master boot record on the third hard disk?

The command that installs GRUB 2 into the master boot record on the third hard disk is the one that correctly utilizes the GRUB installation tools designed for that purpose. The correct answer indicates the use of "grub-install," which is specifically crafted to install the GRUB bootloader on a device.

When you run "grub-install /dev/sdc," you are directly telling the system to install the GRUB 2 bootloader onto the master boot record (MBR) of the specified disk, which in this case is /dev/sdc representing the third hard disk. This command ensures that the bootloader is properly configured to allow the system to boot from that disk.

The other commands, while related to GRUB, serve different purposes. For instance, "grub-mkrescue" is used to create a bootable ISO image or a rescue disk, not to install the bootloader on a physical disk. "grub-setup" can be used, but it generally sets up GRUB 2’s files rather than installs it to the MBR. Therefore, it is not the appropriate command for installing GRUB in the manner described in the question.

Thus, "grub-install" is the precise and correct