GRUB has the power of loading multiple operating systems, including Windows and Mac OS. To do this, it calls the Boot record on the main boot partition, and inserts subsequent calls to other boot records on other boot partitions. This is called-

Chain-loading is the process where a bootloader (like GRUB) loads and passes control to another bootloader located on a partition's boot record, rather than booting the kernel directly. This is commonly used to dual-boot operating systems like Windows and macOS alongside Linux. The other options are incorrect terminology.