During Report,the Nurse Hears That a Patient Is Experiencing Hallucinations

During report,the nurse hears that a patient is experiencing hallucinations.Which is an example of a hallucination?

A) A man believes that his dead wife is talking to him.
B) A woman hears the doorbell ring and goes to answer it, but no one is there.
C) A child sees a man standing in his closet. When the lights are turned on, it is only a dry cleaning bag.
D) A man believes that the dog has curled up on the bed, but when he gets closer he sees that it is a blanket.