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
Goitre is prevalent at higher altitude, is an example of - 
Select and explain. 
A. Direct association, B. Indirect association, C. Causal association, D. Temporal association
B: Indirect association
Answer: B: Indirect association 
Explanation: None