The correct answer is B. cache memory.
Cache memory is a small amount of high-speed memory that is used to store frequently accessed data. This allows the CPU to access data more quickly, which can improve the performance of the computer.
The hard disk is a slower storage device that is used to store programs and data that are not currently being used. When the CPU needs to access data that is stored on the hard disk, it must first read the data from the hard disk and then transfer it to the cache memory. This can take a significant amount of time, which can slow down the performance of the computer.
RAM is a type of memory that is used to store programs and data that are currently being used. It is faster than the hard disk, but it is also more volatile, which means that it loses its contents when the computer is turned off.
Registers are small amounts of high-speed memory that are used to store data that is currently being used by the CPU. They are the fastest type of memory, but they are also the smallest.
Therefore, the most frequently used instructions of a computer program are likely to be fetched from cache memory.