What is the purpose of a process' PID?

The purpose of a process' PID, or Process Identifier, is to uniquely identify each running process in an operating system. Each process is assigned a specific numeric identifier that serves as a way for the system to manage and keep track of running processes. This uniqueness allows the operating system to differentiate between multiple processes that may have similar names or functions, enabling processes to be managed individually. For example, when terminating a process or monitoring its status, the PID is crucial for ensuring that the correct process is targeted.

The other choices relate to different aspects of process management. While priority can influence the scheduling of processes, it is not indicated by the PID itself. Similarly, CPU usage is monitored through various tools and metrics, not directly linked to the PID. File permissions are managed through user and group identifiers, distinct from the function of process identification provided by the PID.