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
Which bullet may produce key hole entry wound? 
Select and explain. 
A. Tracer bullet, B. Tandem bullet, C. Dum-Dum bullet, D. Yawning bullet
D: Yawning bullet
Answer: D: Yawning bullet 
Explanation: Yawning bullet is irregular pattern, thus producing key hole entry wound in some cases.