Colorectal cancer development

Two cohort studies are conducted to investigate the effect of alcohol consumption on colorectal cancer development. Both studies have similar Respiratory rate(RR), but the second study has a wider confidence interval than the first study. What can be concluded from the results of these studies?

A. The second study probably has a smaller sample size than the first study

B. The results of the second study are biased compared to the first study

C. The results of the second study should not be generalized to a larger population

D. The results of the second study are not internally valid