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
Vaccum extraction is done when : 
Select and explain. 
A. Cervix dilated more than 8 cm, B. Persistent occipito posterior, C. Deep transverse arrest, D. All
D: All
Answer: D: All 
Explanation: All