Final answer:
The nurse's most appropriate intervention would be to toilet the patient on a frequent, scheduled basis.
Step-by-step explanation:
The most appropriate intervention for an older adult with Alzheimer's disease who is experiencing fecal incontinence and no recent change in stool character would be option C: Toilet the patient on a frequent, scheduled basis. This intervention helps to establish a routine and promote regular bowel movements, reducing the risk of fecal incontinence. It also ensures that the patient has regular opportunities to use the toilet, promoting continence and reducing the occurrence of accidents.