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
Black gun powder made of -a) Potassium nitrateb) Charcoalc) Sulfur powderd) Cellulose nitratee) Barium sulfate 
Select and explain. 
A. ab, B. abc, C. acd, D. bcd
B: abc
Answer: B: abc 
Explanation: The classical gun powder is known as black powder, consists of charcoal (15%), sulphur (10%), and potassium nitrate (75%).