Sedentary behavior is associated with health risks in adults. A recent article in Clinical Epidemiology reported on a study investigating the effects of replacing objectively assessed sedentary time with time in light-intensity physical activity (PA) or moderate-vigorous PA (MVPA) on all-cause mortality, cardiovas- cular disease (CVD) mortality or cancer mortality in a cohort with 15 years follow-up time. In total, 851 women and men from the population-based Sweden Attitude Behavior and Change study were included. Time spent sedentary, in light-intensity PA and in MVPA were assessed using an accelerometer. Mortal- ity data were obtained from Swedish registers. Over a follow-up of 14.2 years with 12,117 person-years at risk, 79 deaths occurred, 24 deaths from CVD, 27 from cancer, and 28 from other causes. Replacing 30 minutes/day of sedentary time with light-intensity PA was associated with significant reduction in all-cause mortality risk and CVD mortality risk. No statistically significant reductions were found for cancer mortality. In each of the following multiple choice questions, choose the best answer. From this study, can we conclude that a replacing the sedentary time with PA causes a reduction in CVD mortality risk? oa. No, there are too many confounding/lurking factors in the study O b.Yes, because the CVD mortality risk is lower for the PA group Oc Only if the correlation between the two variables is very large Od.No, a volunteer sample can never produce cause and effect