What is the main function of BIOS?

What is the main function of BIOS?

• To enable the graphics card
• To load the operating system
• To upgrade drivers
• To enable the network card 

EXPLANATION

BIOS uses Flash memory, a type of ROM. The BIOS software has a number of different roles, but its most important role is to load the operating system.
When you turn on your computer and the microprocessor tries to execute its first instruction, it has to get that instruction from somewhere.

SOURCE

https://computer.howstuffworks.com/bios1.htm