The answer to this is letter A. The operating system manages files and programs, whilst the BIOS loads the operating system and manages keyboard, screen, and ports. The BIOS is also responsible for checking the hardware of the computer. If there are some things that are not working properly, the BIOS may appear in order to inform the user that there is something wrong.
The operating system will make sure that all of the saved files will remain on the same drive and that the programs will be used properly. The BIOS and the OS would have to work together so that the user can have a smooth-sailing user experience.
Bios check every hardware present or not and detect firmware of every hardware and keep track vender id and product id and keep maintain a teble name sm table.bios start before o.s is calles preboot stage.
o.s maneges every hardware by the help of driver and kernel.o.s placed over hardware.user request to o.s by the help of respective application and o.s talk to the driver and driver talk to firmware of respective hardware.