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
Tattooing in entry wound of a firearm injury is due to: 
Select and explain. 
A. Burns, B. Smoke, C. Gunpowder, D. Wads
C: Gunpowder
Answer: C: Gunpowder 
Explanation: Effects of different discharges from a gun: Fire / Flame -- burning at entrance wound along with burning or singeing of hairs. Smoke - Blackening effect or smudging Hot gases- Scorching effect Unburnt Gun powder - Tattooing effect, peppering or stippling effect Felt wad - Minor abrasion and bruise. Bullet / Pellet - Puncture wound with abrasion collar.