Answer:A.the placebo effect.
Step-by-step explanation:
Our mind can be a powerful tool that has the power to restore our body to health such that one can give you water and tell you if was medicine but the mind believes that and all of a suddenly you feel all well. This can be referred to as a placebo effect when you have been tricked into thinking that you have taken a real medicine and because you believed that you end up feeling healed, eventhough if wasn't the real medicine just the placebo
Placebos are using when testing the effect of new medicine but they are just inactive substances which has no medicinal effect.
It could be sterile water or saline solution. Mr Gotanda just believed the placebo was a real medicine and his mind healed him.