Answer: A. walk up 4 flights of stairs
Step-by-step explanation:
An old person can no longer walk 4 flights of stairs because the joints on their legs can no longer handle that amount of stress .
When one gets older they start to develop many chronic diseases such as high blood pressure , joint pains and these diseases will spike up if they were to expose themselves in such a stressful situation where they have to walk that far and that in a steep level.