Select the cоrrect аnswer: An 81-yeаr-оld pаtient whо was recently admitted to a rehabilitation facility following a hip fracture was prescribed diphenhydramine (Benedryl) to assist with sleep by a covering provider. During today's rounds, staff report that the patient is complaining of constipation and dry mouth. The staff has also noted some periods of mild confusion in this patient. These effects are likely a result of: