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: Social & Preventive Medicine
[{'content': 'Who gave Web of causation theory? \nSelect and explain. \nA. John snow, B. Antonie van Leeuwenhoek, C. Macmahon and Pugh, D. Louis pasteur', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The Web of causation theory was given by Macmahon and Pugh. It is based upon the epidemiological triad of: Agent Host Environment Ref : Park 20/e, Page 32.', 'role': 'assistant'}]