You Go to Work After a Long Weekend and Try

You go to work after a long weekend and try to turn on your computer. When you push the button on the desktop, the system does not start to boot. The monitor turns on and displays a message saying that there's no signal. When you push the desktop button again, you notice that the lights on the computer are turning on, but you don't hear any sounds coming from the desktop.
What is a possible problem with your computer?

A) Power cord is unplugged.
B) Video cable is not connected to the desktop.
C) Hard drive has crashed.
D) Motherboard no longer works.