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
Cause of Farmer's lung – 
Select and explain. 
A. Cotton dust, B. Grain dust, C. Sugarcane dust, D. Iron
B: Grain dust
Answer: B: Grain dust 
Explanation: Farmer's lung is caused by Hay or grain dust.