Based on a case-control study of prostate cancer and cigarette smoking among males, the relative risk of prostate cancer was 1.89 compared to a risk of 1 for non-smokers. What is the attributable risk? a. 1.89 + 1 = 2.89 b. 1.89 - 1 = 0.89 c. (1.89-1)/(1.89) = 0.47 d. 1.89/1 = 1.89