Answer:
Dementia.
Step-by-step explanation:
Dementia is a mental disorder with memory loss, problem-solving, etc. This problem is also found in canines. This disorder occurs due to depression, etc. The symptoms of dementia in canine includes lethargy, sleep disorders, forgetting learned behaviours, etc.
In the given case, the dog who does not react to the sound of a person walking around the house is most likely to suffer from dementia. Dementia causes a canine with the loss of interest in energy and ethusiasm, which is s sign of active canine.
Thus the correct answer is dementia.