You Are Troubleshooting a Computer That Your Client Said Turns

You are troubleshooting a computer that your client said turns off during normal operation. While you are trying to identify the problem, the client also informs you that if he waits a while, the computer will turn back on and run normally for a bit. You open the system and immediately notice a large dust buildup around the processor fan and heat sink.
What problem can you detect on the computer and confidently report to your client?

A) System is overheating.
B) Overclocking has failed.
C) Processor must be replaced.
D) Processor cooling system has failed.