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

startd is not a Linux init system - it is a service management daemon used in Oracle Solaris, not Linux.

systemd is the modern init system and service manager used by most major Linux distributions today, replacing older systems. It uses unit files and targets instead of shell scripts and runlevels.

Upstart is an event-based init daemon developed by Canonical and used in older Ubuntu releases as a transitional replacement for SysV init before systemd became dominant.

SysInit is a fabricated name and does not correspond to any real Linux init system or daemon.

SysV init (System V init) is the traditional Unix init system that uses numbered runlevels and shell scripts located in /etc/rc.d or /etc/init.d to manage services.