You are investigating the role of physical activity in heart disease, and your data suggest a protective effect. whilepresenting your findings, a colleague asks whether you have thought about confounders, such as factor. under which ofthe following conditions could this factor have confounded your interpretation of the data? a. it is a risk factor for some other disease, but not heart disease. b. it is a risk factor associated with the physical activity measure and heart disease. c. it is part of the causal pathway by which physical activity affects heart disease. d. it has caused a lack of follow-up of test subjects. e. it may have blinded your study.