______ is the high speed memory used in the computer.

Option B, hard disk, is a non-volatile storage device that stores data permanently. It is much slower than RAM, but it has a much larger capacity.

Option C, cache, is a small amount of high-speed memory that is used to store frequently accessed data. It is located between the CPU and the main memory, and it helps to improve the performance of the computer.

Option D, BIOS, is a small program that is stored on a chip on the motherboard. It is responsible for initializing the hardware when the computer is turned on, and it provides basic input/output services.