Final answer:
The OTR® is most likely to recommend camouflaging the back door with a poster to prevent the client with Alzheimer's from wandering outside and risking a fall on the stairs.
Step-by-step explanation:
The Occupational Therapist Registered (OTR®) working with a client who has Stage III Alzheimer's disease and is prone to wandering would likely recommend using a poster to camouflage the back door and the door knob. This strategy is known as a visual barrier technique and can help to prevent the client from recognizing the door as an exit, thereby reducing the risk of falls.
The poster can disguise the back door sufficiently to dissuade the client from attempting to navigate potentially hazardous stairs. Painting a STOP sign or using contrasting colors might not be effective for someone with cognitive impairment, as it may not deter the behavior, and an alarm or motion-detecting light could be disorienting or distressing for the client.