Which of the following is the main a non-volatile storage device used in computers?0.5 MarksHard diskRAMUSB flash driveCache memory

To identify the main non-volatile storage device used in computers from the given options, we need to understand what non-volatile storage means. Non-volatile storage retains information even when the power is turned off, unlike volatile storage (e.g., RAM), which loses data when the power is lost.

1. Hard Disk: This is a common non-volatile storage device that stores data permanently until it is deleted.
2. RAM (Random Access Memory): This is a volatile memory that loses its data when the computer is turned off.
3. USB Flash Drive: This is also a non-volatile storage device but is typically used for portable storage.
4. Cache Memory: This is a small-sized type of volatile memory providing high-speed data access to the processor.

Considering these definitions, the Hard Disk is the main non-volatile storage device used in computers among the options provided.

In summary, the answer is:

Final Answer: Hard disk