正解:B
The technician has already determined that the desktop PC has failed due to a defective power supply. The next step is to conduct research to determine the cause of the failure. This could involve looking at the power supply's specifications, checking for any recalls, or researching similar failures that have occurred in the past.
Once the technician has a better understanding of the cause of the failure, they can then develop a plan of action to resolve the problem. This could involve replacing the power supply, repairing the power supply, or upgrading the power supply.
The technician should also document the findings, actions, and outcomes of their troubleshooting process. This documentation will be helpful in the event that the same problem occurs again in the future.