GRUB 2 is a versatile bootloader that can directly load various operating system kernels, such as Linux, because it understands their executable formats. For proprietary systems like Windows, it uses a method called chain-loading, where it loads the other system's bootloader and passes control to it. A significant advancement in GRUB 2 over its predecessors is its native support for various filesystems (e.g., ext4, XFS, Btrfs). This allows it to locate and load the kernel and initial RAM disk files by their pathnames, eliminating the need to know their physical block locations on the storage device.

A. The correct path for the user-editable configuration file is /etc/default/grub, not /etc/default/grub2.

C. The main GRUB 2 configuration file is named grub.cfg (located in /boot/grub2/), not grub2.conf.

1. Oracle® Linux 8: Managing Core System Configuration

Chapter 3. Managing the Boot Loader.

Section 3.1

"About the GRUB 2 Boot Loader": States

"GRUB 2 can read file systems such as Btrfs

ext4

and XFS

which means that it can access files on a device by file name... GRUB 2 can also chain load another boot loader to boot operating systems such as Windows." This directly supports options B and D.

Section 3.2

"GRUB 2 Configuration": Specifies

"The main configuration file for GRUB 2 is /boot/grub2/grub.cfg... You should not edit this file directly. Instead

you should edit the /etc/default/grub file..." This confirms that options A and C use incorrect file names.

2. GNU GRUB Manual 2.06

Chapter 3. GRUB image files.

Section 3.1

"An overview of the boot process": Explains

"GRUB has a knowledge of filesystems... This means that you can specify a kernel image by a file name... without having to worry about the physical location of the kernel image on a disk." This validates option D.

Section 6.3

"Chain-loading": Describes the chainloader command

which is used to "load a boot loader for another operating system". This validates option B.