This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': 'Problem of bias is maximum with \nSelect and explain. \nA. Coho study, B. Case study, C. Case control study, D. Experimental study', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Bias is any systemic error in the determination of the association between exposure and disease. The relative risk may increase or decrease as a result of the bias it reflects some type of no compatibility between the study and control groups. The possibility of bias must be considered when evaluating a possible cause and effect relationship. (refer pgno 73, park 23rd edition)', 'role': 'assistant'}]