A nurse is reviewing the medical record of a client who is experiencing delirium. Which of the following medications should the nurse identify as a cause of this disorder?

The correct answer is D: Antihistamines. Delirium is a common side effect of antihistamines due to their sedative effects on the central nervous system. Antihistamines can cause confusion, disorientation, and cognitive impairment, leading to delirium. Benzodiazepines (choice A) can also cause delirium but are more commonly associated with sedative withdrawal. Sertraline (choice B) is an antidepressant and not typically associated with delirium. Amphetamines (choice C) are stimulants and can cause agitation or psychosis but not typically delirium. Therefore, the nurse should identify antihistamines as the medication most likely causing the client's delirium.