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: Unknown
Ratio of incidence of a disease among the exposed to the incidence among non-exposed is: 
Select and explain. 
A. Odds ratio, B. Relative risk, C. Absolute risk, D. Attributable risk
B: Relative risk
Answer: B: Relative risk 
Explanation: Ref. Foundations of Community medicine. Page. 596
 
Measures of effect

Measures of effect are used in epidemiological studies to assess the strength of an association between a putative risk factor and the subsequent occurrence of disease.
This requires that the incidence of disease in a group of persons exposed to a potential risk factor is compared with the incidence in a group of persons not exposed to the potential risk factor.
This comparison can be summarized by calculating either the ratio of measures of disease frequency for the two groups or the difference between the two, and reflects the increase in frequency of disease in one population compared with another, treated as baseline.

 
Three main measures of effect