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
"Calibre" of fire arm is: 
Select and explain. 
A. Distance between land and groove, B. Distance between two lands, C. Distance between two grooves, D. None
B: Distance between two lands
Answer: B: Distance between two lands 
Explanation: Distance between two lands