Explanation:

The three fundamental components that constitute a general-purpose computer system are the Central Processing Unit (CPU), which performs all processing; Input/Output (I/O) Devices, which allow interaction with the user and external systems; and Main Memory (RAM), which stores data and instructions for the CPU to access quickly. Option (a) correctly lists these three categories: RAM (Main Memory), Input/Output Devices, and Central Processing Unit. Options (b), (c), and (d) list specific types of storage or output devices alongside the CPU, but they do not represent the three broad, essential categories of a computer's architecture.