This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Cancer, Subject name: Pharmacology
Mechanism of action of tacrolimus - 
Select and explain. 
A. Folate antagonist, B. Calcineurin inhibitor, C. Antimetabolite, D. CD 20 antibody
B: Calcineurin inhibitor
Answer: B: Calcineurin inhibitor 
Explanation: Ans. is 'b' i.e., Calcineurin inhibitor