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
Most commonly used blinding technique in epidemiological studies 
Select and explain. 
A. Single blinding, B. Triple blinding, C. Double blinding, D. None of the above
C: Double blinding
Answer: C: Double blinding 
Explanation: Blinding

The blinding is used to prevent outcomes from being influenced by the bias. Blinding is a basic tool to prevent concious as well as subconcious bias in the study.
To blind a person involved in the study (subject, investigator or observer) is to prevent them from knowing certain information about the study