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: Forensic Medicine
Caliber of a rifled gun is calculated: DNB 09; TN 11; AIIMS 14 
Select and explain. 
A. Distance between a land and groove, B. Distance between two diagonally opposite lands, C. Distance between two diagonally opposite grooves, D. Number of spherical lead balls that can be made from one pound of lead
B: Distance between two diagonally opposite lands
Answer: B: Distance between two diagonally opposite lands 
Explanation: Ans. Distance between two diagonally opposite lands