This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
The diameter of fetal head, which comes in totally deflexed head : 
Select and explain. 
A. Suboccipito-frontal, B. Occipito-frontal, C. Submento-bregmatic, D. Suboccipito-bregmatic
B: Occipito-frontal
Answer: B: Occipito-frontal 
Explanation: Circumferences of the head in different attitudes: -- Complete flexion Biparietal-suboccipito-bregmatic. Shape -- almost round 27.5 cm (11") -- Deflexed Biparietal-occipito-frontal. Shape -- oval 34 cm (13 1/2 ") -- Incomplete extension Biparietal-mento-veical. Shape -- bigger oval 37.5 cm (15") -- Complete extension Biparietal-submento-bregmatic. Shape -- almost round 27.5 cm (11") Reference: D C Dutta Textbook of Obstetrics 7th edition,page 85.