May you explain your question a little bit better?
It seems that you have missed the necessary options for us to answer this question, so I had to look for it. Anyway, here is the answer. Since Mary is employed by a multinational firm, and works long hours on a desktop computer and has recently experienced back pain and visited her doctor, the guideline that <span> the doctor would advise Mary to follow is this: SIT BACK ON THE CHAIR. Hope this helps.</span>
