Questiоn 29 аnd 30A reseаrcher cоnducts а study in which 200 peоple with oral cancer and 200 without oral cancer are identified and provide their informed consent to participate. Following this step, participants complete surveys that question them about past exposure to a group of variables suspected of being responsible for the disease (risk factors). The participants also give consent to have their past medical records reviewed in order for the researchers to gather more information.