The correct answer is A. Control unit.
A control unit is a part of the central processing unit (CPU) that coordinates the execution of instructions by fetching instructions from memory, decoding them, and sending appropriate signals to other parts of the CPU. It also controls the flow of data between the CPU and other devices.
A communications processor is a device that is used to control the flow of data between two or more devices. It is typically used in networks to control the flow of data between computers.
A register unit is a part of the CPU that stores data and instructions that are currently being used. It is a small amount of high-speed memory that is used to store data that is needed immediately by the CPU.
A CPU is the main processing unit of a computer. It is responsible for carrying out the instructions that are stored in the computer’s memory.
E is not the correct answer because it is not a type of processing unit.