Ruthie is an elderly woman and has a very high fever. She normally is pretty sharp, but with this high fever she seems to be almost out of her mind. She doesn't remember what she is doing, can't sustain a conversation, and is generally confused about any decisions that have to be made. A week or so later, the fever subsides and Ruthie seems back to her normal self. While the fever was high, Ruthie experienced a. Parkinson's disease. b. delirium. c. dementia. d. Alzheimer's disease.