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': 'Goitre is prevalent at higher altitude, is an example of - \nSelect and explain. \nA. Direct association, B. Indirect association, C. Causal association, D. Temporal association', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]