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
Most unourable presentation for vaginal delivery is / delivery not possible per vaginum is : 
Select and explain. 
A. Mento posterior, B. Mento anterior, C. Occipito posterior, D. Deep transverse arrest
A: Mento posterior
Answer: A: Mento posterior 
Explanation: Mento posterior