This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Anatomy
All of the following drugs are effective for cervical ripening during pregnancy except : 
Select and explain. 
A. Prostaglandin E2, B. Oxytocin, C. Progesterone, D. Misoprostol
C: Progesterone
Answer: C: Progesterone 
Explanation: Ripening of cervix is changing the cervical matrix from sol to gel state by dissolving the collagen bundles making cervix soft. Drugs used for cervical ripening are: Prostaglandin - Dinoprostal gel and Misoprostal tablet Steroid receptor antagonist - Mifepristone, Onapristone Relaxin Glyceryl trinitrite, isosorbide mononitrate Oxytocin Ref: Williams Obs 24e pg 525,Datta Obs 9e pg 486.