This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Tacrolimus belong to which class of drug ? 
Select and explain. 
A. Calcineurin inhibitor, B. mTOR inhibitor, C. Hypoxathine inhibitor, D. Inosine inhibitor
A: Calcineurin inhibitor
Answer: A: Calcineurin inhibitor 
Explanation: Ans. is 'a' i.e., Calcineurin inhibitor