Your troubleshooting a malfunctioning notebook computer system. The user has indicated that the screen is always dark and difficult to read even while the system is plugged into a wall outlet. You check the system and determining the back light isn't working. Which of the following could be the cause
– The notebook video adapter is malfunctioning
– The notebook battery is failing and needs to be replaced
– The LCD cut off switch is stuck in the off position
– The wrong AC adapter is being used with the system