Troubleshooting a laptop display

One of your customers has called with a problem related to the laptop’s LCD display. Although the laptop’s display had been working normally yesterday, when starting the laptop this morning the LCD display remained blank. What’s the best option for troubleshooting the LCD display?

A) Upgrade the BIOS to the latest version

B) Reinstall the operating system from the original installation media

C) Reboot the laptop until the LCD display begins to operate normally

D) Power down the laptop, connect an external monitor, and power on the laptop