Answer:
A. Processor.
Step-by-step explanation:
When a computer system works working or does not boot, it is mostly ask a result of power supply failure.
The system does not come on, that is, the fan and screen does not come up and the caps lock indicator is not blinking. The power supply shows that the power is good.
When the processor is not sitting properly and when the motherboard has failed, the signs mentioned above are observed.
Not to escalate the problem, test for the processor status as a probable cause with another functional and compatible processor before the motherboard.