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': 'Main purpose of Randomisation is \nSelect and explain. \nA. To eliminate selection Bias, B. To remove confounding factor, C. For good results, D. To eliminate Analysis Bias', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]