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
Best indicators of the pollution 
Select and explain. 
A. Soiling Index, B. Air pollution Index, C. Sulphur dioxide, D. Breteau Index
C: Sulphur dioxide
Answer: C: Sulphur dioxide 
Explanation: None