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
Mifepristone used for medical abortion is: 
Select and explain. 
A. Anti estrogen, B. Anti progesterone, C. Anti folate, D. Prostaglandin derivative
B: Anti progesterone
Answer: B: Anti progesterone 
Explanation: None