Which one among the following is a main system board of a computer?

The correct option is Mother board.

Step-by-step explanation:

1. Understanding the Motherboard: The motherboard (often referred to as the main system board, mainboard, or mobo) is the primary printed circuit board (PCB) in a computer. It serves as the central hub that connects all the vital components of the system.

2. Role and Connectivity: The motherboard houses critical components such as the Central Processing Unit (CPU), system memory (RAM), and connectors for input/output devices. It provides the electrical pathways (known as buses) that allow these hardware components to communicate with one another.

3. Analyzing the Other Options:
- CPU (Central Processing Unit): This is the "brain" of the computer responsible for executing instructions, but it is an integrated circuit chip that plugs into the motherboard, not the main system board itself.
- Keyboard: This is an external input device used for typing, which connects to the motherboard via ports.
- Microchip: This is a general term for any integrated circuit. While the motherboard contains many microchips, the term does not refer to the main board itself.

Therefore, the motherboard is the main system board of a computer that integrates and allows communication between all its crucial parts.