This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Obstetrics, Subject name: Gynaecology & Obstetrics
Which of the following is the engaging diameter in the fetus in left occiput anterior (LOA) position: 
Select and explain. 
A. Suboccipito - bregmatic, B. Mento-veical, C. Sub-Mento bregmatic, D. Sterno-Bregmatic
A: Suboccipito - bregmatic
Answer: A: Suboccipito - bregmatic 
Explanation: Position of Head Presentation Engaging diameter Well flexed head Veex presentation Sub-Occipito bregmatic, 9.5 cms Deflexed head Sinciput presentation Occipito-frontal , 11.5cms Paial extended Brow presentation Mento veex, 14 cms Fully extended head Face presentation Submentobregmatic ,9.5cms or submentoveical 10 cms