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': 'Gun powder in hand during gun-shot residue is collected using:- \nSelect and explain. \nA. Paraffin wax, B. Benzidine, C. Acid phosphatase, D. Sulfur', 'role': 'user'}, {'content': 'Answer: A \nExplanation: * Paraffin test aka dermal nitrate test is an absolete test, uses melted paraffin on the surface of hand. The wax is removed & its inner surface is treated with diphenylamine or diphenyl benzidine reagent. A blue color develops when residue is present.', 'role': 'assistant'}]