Which component is primarily responsible for executing instructions from software?

The Central Processing Unit (CPU) is primarily responsible for executing instructions from software. Often referred to as the "brain" of the computer, the CPU interprets and processes commands from programs, performing calculations and making decisions based on the data it receives. It operates by fetching instructions from memory, decoding them, and then executing them sequentially. This ability to perform complex computations and manage multiple tasks makes the CPU essential for the overall functionality of any computing device.

In contrast, the Graphics Processing Unit (GPU) is designed specifically for rendering images and handling graphical tasks, rather than general-purpose instruction execution. Random Access Memory (RAM) serves as temporary storage for data and instructions that the CPU is currently processing, but it does not execute instructions itself. The Hard Disk Drive (HDD) is a storage device that retains data permanently, but it also does not execute software instructions. Therefore, the CPU's unique role in executing instructions makes it the correct choice in this context.