A user creates a support ticket to report a conference room projector that does not work. The user says that even though the provided cables are being used, the projector screen shows the following error message:
No Signal Input
Which of the following describes the FIRST action that should be taken?


A. Verify that the projector is turned on.
B. Verify that the user is using an approved OS.
C. Replace the projector bulb.
D. Check the video cable and replace it if necessary.