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: Microbiology
The smallest anteroposterior diameter of the pelvic inlet is called the 
Select and explain. 
A. Interspinous diameter, B. True conjugate, C. Diagonal conjugate, D. Obstetric conjugate
D: Obstetric conjugate
Answer: D: Obstetric conjugate 
Explanation: The obstetric conjugate is the shoest distance between the promontory of the sacrum and the symphysis pubis. It generally measures 10.5 cm. Because the obstetric conjugate cannot be clinically measured, it is estimated by subtracting 1.5 to 2 cm from the diagonal conjugate, which is the distance from the lower margin of the symphysis to the sacral promontory.