Final answer:
Autoruns is the utility designed to show all programs that are set to run automatically when a computer boots up, making it the correct choice for identifying auto-starting software on a PC.
Step-by-step explanation:
The tool that can help a support specialist identify which software starts automatically on a PC is c) Autoruns. Autoruns is a utility that provides comprehensive details on everything that runs automatically when a computer starts up. It encompasses auto-starting locations of any startup monitor, from registry entries to scheduled tasks, and beyond. Unlike Task Manager, which mainly shows applications currently running on the system, or Disk Cleanup, which is used to free up disk space, Autoruns is specifically designed to show which programs are configured to run during system bootup or login. The Registry Editor can also show which programs start automatically, but it’s much less user-friendly and could be risky if used improperly, especially for those not familiar with Windows registry operations.