Your question is Linux Boot Process Explanation. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Describe the Linux boot process. Cover the path from firmware initialization through the bootloader, Linux kernel, initramfs, and the first userspace process. Explain where systemd fits, how the root filesystem becomes available, and how you would investigate a boot failure. Scope your answer to a typical modern x86_64 Linux system using UEFI and systemd, while noting important BIOS differences.