What is the definition of POST?

The correct definition of POST, which stands for Power-On Self-Test, is that it is a diagnostic test of the computer's hardware for presence and operability during the boot sequence prior to running the operating system. This process occurs immediately after the computer is powered on and is essential for ensuring that all critical hardware components, such as the CPU, memory, and storage devices, are functioning correctly before the operating system is loaded. During POST, the system checks for the presence of essential hardware and verifies that it is operational, helping to prevent boot failures caused by hardware malfunctions.

While other options mention diagnostic tests related to software or a combination of software and hardware, POST specifically focuses on hardware diagnostics. The emphasis is on ensuring that the necessary hardware components are present and working correctly, which is crucial for a successful boot process.