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
While analysis of data, allocation into similar groups is done to ensure- 
Select and explain. 
A. Comparability, B. Accuracy, C. Validity, D. Sensitivity
A: Comparability
Answer: A: Comparability 
Explanation: In a case-control study, the controls may differ from cases in a number of factors like age, sex, occupation. - it is necessary to ensure comparability between cases and controls. - this process is called matching. Reference: Park's textbook of preventive and social medicine, 23rd edition, pg no:72