Correct option is A
Option (a) is correctly spelt word.
Correct spelling is: “Psychopharmacology”. It is the branch of psychology/medicine that studies how drugs affect the mind, emotions, and behaviour (i.e., the psychological effects of medications and other substances). (Hindi: मनो-औषधि विज्ञान / दवाओं के मानसिक प्रभावों का अध्ययन)
Example: Psychopharmacology helps doctors understand how antidepressants influence mood and cognition.