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: Medicine
Farmer's lung is caused by exposure to - 
Select and explain. 
A. Cryptostroma corticale, B. Asperigullus, C. Thermophilic actinomycetes, D. Grain dust
C: Thermophilic actinomycetes
Answer: C: Thermophilic actinomycetes 
Explanation: None