An 85-year-old male is brought to the emergency department by his family who report he has become acutely confused, disoriented, and agitated over the past 24 hours. He has a known history of mild memory impairment that has been stable for years. Which feature is most characteristic in differentiating delirium from dementia?
✓ Correct Answer: Option C
Delirium is characterized by an acute onset, fluctuating course, and disturbances in attention and level of consciousness. Dementia typically has a gradual onset, a progressive course, and preserved attention in early stages.