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: Gynaecology & Obstetrics
What type of uterine contraction is responsible for cervical ripening ? 
Select and explain. 
A. A waves, B. B waves, C. Both, D. None
D: None
Answer: D: None 
Explanation: None