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
30 out of 50 smokers and 10 out of 50 non smokers develop lung cancer. What is odd's Ratio 
Select and explain. 
A. 4, B. 2.8, C. 6, D. 7
C: 6
Answer: C: 6 
Explanation: None