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
All of the following are true about case control study except ? 
Select and explain. 
A. Rapid and inexpensive, B. No risk to subjects, C. Risk factor can be identified, D. Less prone to bias
D: Less prone to bias
Answer: D: Less prone to bias 
Explanation: Ans. is 'd' i.e., Less prone to bias