This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis of Pregnancy, Subject name: Gynaecology & Obstetrics
After childbih, the external cervical os is: 
Select and explain. 
A. Regular, oval, B. Transverse, C. Longitudinal, D. Irregular, oval
B: Transverse
Answer: B: Transverse 
Explanation: Before childbih, the external cervical os is a small, regular, oval opening. After childbih, the orifice is conveed into a transverse slit that is divided such that there are the so-called anterior and posterior lips of the cervix.