What is contained in a computer's BIOS?

• A. The Basic Input Output System which is read by the CPU, containing the instructions for a computer to boot up properly like copying the OS onto the RAM and performing self-checks e.g. testing memory and hardware is working
• B. The user data and files
• C. The operating system kernel
• D. Temporary cache memory

Answer: (A)

At startup, the BIOS is firmware that the CPU runs to get the computer ready. It sits on a chip and contains the instructions to initialize basic hardware, run a power-on self-test to check memory and devices, and begin the boot process by locating the bootloader to start loading the operating system.

In practice, the BIOS (or modern UEFI) doesn’t copy the entire OS into RAM by itself. Instead, it performs the initial checks and then hands control to a small bootloader that loads the OS into memory. This bootstrapping is why the BIOS is essential for booting, but it doesn’t hold the user data, the OS kernel itself, or the temporary cache in RAM.

The other options don’t fit because user data and files reside on storage, the operating system kernel is loaded after the boot process, and temporary cache memory is part of RAM, not firmware.