The correct answer is: D. All of the above
The central processor of a modern digital computer consists of the control unit and primary memory. The control unit is responsible for fetching instructions from memory, decoding them, and executing them. Primary memory is where the program and data are stored while the computer is running.
The control unit is a hardware component that manages the operation of the computer. It fetches instructions from memory, decodes them, and executes them. The control unit also controls the flow of data between the CPU, memory, and input/output devices.
Primary memory is a hardware component that stores data and instructions that are currently being used by the CPU. Primary memory is also known as RAM (random-access memory). RAM is volatile, which means that it loses its contents when the power is turned off.
The control unit and primary memory are essential components of the central processor. Without them, the computer would not be able to execute instructions or store data.