- A) Electronic computer

A microprocessor is an electronic computer on a single integrated chip that functions as the CPU. A memory disk is an external storage device, not a core component that describes what a microprocessor is. Memory disks store data but are separate from the processor itself—they do not define or describe the microprocessor.

Step-by-step Derivation:
A microprocessor is fundamentally: (1) an electronic computing device, (2) a CPU that executes instructions, and (3) a single integrated circuit chip. Options A, B, and D all accurately describe a microprocessor's nature. Option C (Memory disk) describes secondary/external storage media, which is architecturally distinct from the processor. A memory disk cannot execute instructions and is not part of the microprocessor's core definition.