Final answer:
A technician can locate the PID of an application using the Task Manager, which provides information on running processes and their identifiers.
Step-by-step explanation:
The tool from which a technician can locate the PID (Process ID) of an application is the Task Manager. The Task Manager provides detailed information about the programs and processes running on the computer.
By opening Task Manager and navigating to the 'Details' tab, the technician can see a list of all running processes along with their corresponding process identifiers (PIDs).