What is the main purpose of the Power$-$On Self$-$Test $($POST$)?$

A$.$The computer performs a Power$-$On Self$-$Test $($POST$)$ to check that monitor display settings are correct.

B$.$The computer performs a Power$-$On Self$-$Test $($POST$)$ to ensure the printer powers up correctly.

C$.$The computer performs a Power$-$On Self$-$Test $($POST$)$ to check that the main components work and then loads the Operating System.

D$.$The computer performs a Power$-$On Self$-$Test $($POST$)$ to check that the computer is plugged in and receiving power.