This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
Randomization is done in clinical trials to: 
Select and explain. 
A. Avoid selection bias inside the study group, B. To avoid bias from general population, C. To eliminate comparability, D. Option not recalled
A: Avoid selection bias inside the study group
Answer: A: Avoid selection bias inside the study group 
Explanation: Ans. A. Avoid selection bias inside the study groupExplanationRandomization is a statistical procedure by which participants are allocated to study and control groups in a Randomized control trail.Randomization is the heart of a control trial. It ensures investigator has no control over allocation process and thus eliminates selection bias and thus every individual gets equal chance of being allocated to either of the groups.By definition distortions that result from procedures used to select subjects and from factors that influence participation in the study is called selection bias.The estimated effect of cigarette smoking on heart disease will be biased if study participants are volunteers and the decision to volunteer is affected by smoking status.