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': 'Most difficult criterion to establish Causal Association in aetiology of a disease is \nSelect and explain. \nA. Specificity of association, B. Strength of association, C. Temporality, D. Biological plausibility', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]