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
Who gave Web of causation theory? 
Select and explain. 
A. John snow, B. Antonie van Leeuwenhoek, C. Macmahon and Pugh, D. Louis pasteur
C: Macmahon and Pugh
Answer: C: Macmahon and Pugh 
Explanation: 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.