This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Gynaecology & Obstetrics
Smallest pelvic diameter is 
Select and explain. 
A. True conjugate, B. Interspinous diameter, C. Inteuberous diameter, D. Posterior sagittal diameter
B: Interspinous diameter
Answer: B: Interspinous diameter 
Explanation: The interspinous diameter is 10 cm or slightly greater, is usually the smallest pelvic diameter, and, in cases of obstructed labor, is paicularly impoant.(Ref: William's Obstetrics; 25th edition)