Which of the Following Statements Is True Regarding Systemd Timer

Which of the following statements is true regarding systemd timer units?

A) Timer units can only be defined within a service unit's file.
B) The command executed by the timer is specified in the timer unit's [Cmd] section. The command executed by the timer is specified in the timer unit's [Cmd] section.
C) A dedicated system service, systemd-cron , handles the execution of timer units. A dedicated system service, systemd-cron , handles the execution of timer units.
D) Timer units only exist in the system scope and are not available for users.
E) Each systemd timer unit controls a specific systemd service unit.