Answer:
It would either be the motherboard or the CPU.
Step-by-step explanation:
"The part of the computer that contains the brain" is an odd way to put it. It would either be the motherboard or the CPU. The motherboard helps all the components work as one essentially preforming as one may call it a "brain". However, it can also be said that a CPU is alike in how a brain functions by processing information to other parts of the computer.