Episodes of Delirium Are Common with the Ill and the Elderly

Episodes of delirium are common with the ill and the elderly because ____.

A) they have less cerebral reserve and are likely to develop delirium with medical illness or surgical procedures
B) their immune systems are compromised and are likely to develop delirium with medical illness or surgical procedures
C) they are susceptible to infection-produced inflammation of tissues surrounding the brain and are likely to develop delirium with medical illness or surgical procedures
D) delirium is as common among the ill and elderly as it is in the general population