Mr.Gabbard,79 years old,is hospitalized for an exacerbation of congestive heart failure.He does not recognize his daughter and wonders why his wife,who died years ago,has not visited him.What is Mr.Gabbard most likely experiencing?

A) Delirium
B) Sensory overload
C) Dementia
D) Acute sensory deficit

Mr. Gabbard is most likely experiencing delirium, which is a sudden change in mental status characterized by confusion, disorientation, and impaired thinking. It is commonly seen in elderly patients who are hospitalized or are suffering from an acute illness. Delirium can cause perceptual disturbances, such as hallucinations or delusions, which may explain Mr. Gabbard's belief that his wife has not visited him even though she is deceased.