Which run level is designated for shutting down the system?

The run level designated for shutting down the system is 0. In the init system used in many Unix-like operating systems, run levels are used to define the state of the machine.

Run level 0 specifically indicates that the system is halted and is in the process of stopping and shutting down all services. It is essentially the state where the system is safely powered off, making it the correct answer for this question.

In contrast, other run levels serve different purposes, such as run level 1, which is single-user mode for administrative tasks without networking, run level 3 for multi-user mode with networking but without a graphical user interface, and run level 6 for a system reboot. Understanding the role of each run level is important for managing the system's operational state effectively.