Which of the following are init systems used within Linux systems? (Choose THREE correct answers.)

'startd' is not a recognized or standard init system in Linux.

systemd is the current default and widely adopted init system in many modern Linux distributions, managing processes and services after the kernel boots.

Upstart was an event-based init system developed by Ubuntu, used in several distributions before the widespread adoption of systemd.

'SysInit' is not a recognized or standard init system in Linux; it's a generic term, not a specific system.

SysV init (System V init) is the traditional and oldest init system used in many Unix-like operating systems and older Linux distributions, managing processes via runlevels and scripts.