What is the main sequence of the computer's startup process?

The main sequence of the computer's startup process begins with the power being turned on, initiating a series of events to prepare the system for use.

First, when power is supplied to the computer, the BIOS (Basic Input/Output System) or UEFI (Unified Extensible Firmware Interface) firmware is loaded. This firmware is crucial as it acts as an intermediary between the hardware and the operating system. It performs POST (Power-On Self-Test), which runs diagnostic tests to ensure that the hardware components (like RAM, CPU, and storage devices) are functioning correctly.

After successfully completing the POST, the BIOS/UEFI identifies the bootable devices and selects a boot device from where the operating system can be loaded, such as a hard drive or SSD. This step is critical because it sets the path for the operating system's kernel to be loaded into the computer’s memory for further operations.

Following this sequence ensures that all necessary hardware components are operational and ready to run the operating system, making option B the accurate representation of the computer's startup process.