Questiоn 3g: Suppоse yоu were interested in conducting а retrospective cohort study of аll firefighters in Floridа to determine if occupational exposure to potential known and unknown carcinogens increased esophageal cancer among firefighters. You use available data through a firefighter employment record database. This database provides you with information on past and current employment as a firefighter for the past 20 years. It also includes demographic information (i.e., age, race/ethnicity, biological sex), pay scale (e.g., firefighter level 1), job classification (e.g., engineer), as well as health information from the required annual physicals (i.e., alcohol consumption, smoking status, vital signs, bloodwork, urinalysis, pulmonary function tests, hearing and vision tests). In addition to this database, you have access to the event reporting system that allows you to track all incidents (e.g., fire call, medical call) a particular firefighter responded to over the course of the year. This reporting database provides you with information on potential occupational exposures to known and unknown human carcinogens. Finally, you link to the Florida state cancer registry to determine esophageal cancer diagnoses. Briefly describe one challenge that you would face in operationalizing this study related to selecting participants for your study and one challenge related to measurement.