A 95% Cl for the relative risk is (0.2 to 0.8). How would you interpret this confidence interval? Select one: O a. The interval excludes 0, therefore it is insignificant. O b. The interval excludes 0, therefore it is significant. O c. The interval excludes 1, therefore it is insignificant. O d. The interval excludes 1, therefore it is significant. Specificity is calculated as: Select one: O a. Total positive / Total total O b. True positive / Total diseased O c. True negative / Total non-diseased O d. Total positive / Total negative ge