Medical researchers investigated the association between the risk of fatality from lung cancer and risk factors associated with asbestos work and smoking. In the study, 50,000 participants were surveyed about their exposure to asbestos and their smoking habits. Data from the research is summarized in the table below. Risk factors Asbestos worker, non-smoker Asbestos worker, smoker Risk of fatality from lung cancer 5% 53% Identify the independent variable in the experiment. Choose 1 answer: risk factors the 48% increased risk for smokers the 5% risk for nonsmokers relative risk of fatality from lung cancer