This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ballistics, Subject name: Forensic Medicine
[{'content': 'Which of the following is not altered by rifling a gun? \nSelect and explain. \nA. Prevents wobbling of the bullet, B. Improves greater power of penetration of bullet, C. Decreases the smoke from the barrel, D. Impas gyroscopic stability of bullet', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Advantages of rifling a gun: Impas gyroscopic stability Increases accuracy and range Prevents wobbling or tumbling end-over-end Gives greater power of penetration', 'role': 'assistant'}]