The correct answer is: C. System board.
The system board, also known as the motherboard, is the main circuit board of a computer. It contains the CPU, BIOS, RAM, and other essential components. The system board is responsible for initializing the CPU and other components during the boot process. It also provides a connection point for other components, such as expansion cards and storage devices.
The expansion memory board is a circuit board that can be added to a computer to increase the amount of memory available. The video adapter is a circuit board that is responsible for displaying images on a monitor. The cache is a small amount of high-speed memory that is used to store frequently accessed data.
While the expansion memory board, video adapter, and cache can all affect the amount of memory available to a computer, they are not responsible for initializing the memory during the boot process. The system board is the only component that is responsible for this task.