This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Anatomy
The barrel is scored internally with a number of shallow spiral grroves, called 
Select and explain. 
A. Rifling, B. Choking, C. Blackening, D. Tattooing
A: Rifling
Answer: A: Rifling 
Explanation: Rifles The barrel is scored internally with a number of shallow spiral grooves varying from 4-7 and most commonly 6. These grooves are called rifling. Ref: FORENSIC MEDICINE AND TOXICOLOGY Dr PC IGNATIUS THIRD EDITION PAGE 136