Concept:Computer hardware is broadly grouped into the system unit and all external devices attached to it.
Explanation:The system unit is the main body of the computer that holds the internal processing components.
Peripherals are devices connected to the system unit, such as the keyboard, mouse, monitor, and printer.
Together, the system unit and peripherals make up the complete computer hardware.
The motherboard, control unit, and central processing unit are all parts found inside the system unit, not separate major divisions of hardware.
Hence, the correct pair of hardware divisions is system unit and peripherals.
Answer:B. peripheral