What component is primarily responsible for executing instructions in a computer?

The component primarily responsible for executing instructions in a computer is the CPU, or Central Processing Unit. The CPU, often referred to as the "brain" of the computer, carries out the commands of a computer program by performing basic arithmetic, logical, control, and input/output operations. It interprets and executes instructions from the computer's memory, processes data, and coordinates communication between various hardware components.

In contrast, the hard drive serves as the storage device for data and programs but does not execute instructions. Memory, or RAM, temporarily holds data and instructions that the CPU frequently accesses during operations, but it is the CPU that ultimately processes those instructions. Meanwhile, the power supply unit provides the necessary electrical power to all components of the computer, ensuring they have the energy needed to function, but it does not play a role in instruction execution. Therefore, the CPU is central to the computing process, executing the instructions that drive software applications and overall system functionality.