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
[{'content': 'When two objects come in contact, an exchange of trace material takes place. This is known as: PGI 08 \nSelect and explain. \nA. Galton exchange, B. Locard exchange principle, C. Beillion system, D. Hasse rule', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Locard exchange principle', 'role': 'assistant'}]