Which statement made by a family member tends to support a diagnosis of delirium rather than dementia?
a. "My grandmother has been forgetful lately, but she's always been that way."
b. "My father seems confused and disoriented, and his symptoms came on suddenly."
c. "My mother has been repeating herself a lot, and it's been going on for several years."
d. "My sister has been having trouble with her memory, but she's still able to recognize everyone."