ANS:A - Core memory

CPU register : is a small amount of data storage, that facilitates some CPU operations, or it is one of a small set of data holding places that are part of the computer processor.

CPU cache : it is a high-speed volatile memory which is bigger in size, that helps the processor to reduce the memory operations.

It is a smaller, faster memory, closer to a processor core, which stores copies of the data from frequently used main memory locations.