What is modified when changing the system start-up boot sequence?

BIOS/CMOS

A. BIOS:  the first action of a PC is copying the BIOS program from CMOS to RAM when you turn it on. The BIOS program is responsible for detecting and listing the devices/components of a PC. It also perform some testing and error reporting at the basic level. During the detection process it detects all the bootable devices and connections. At the last stage of BIOS activity it looks for booting information from the bootable devices it detected according to the boot sequence configured in the BIOS. If it finds the right information from any detected device then it initiates the OS loading from it. Other3 options B, C & D are the files which describes the list and sequences  of OS related files and commands to load and execute.

A

BIOS

Changing the boot sequence of a windows-based computer can be done very simply by entering the computer's basic input/output system (BIOS) settings.

A