This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'A local restaurant was the focus of a botulism outbreak.\nThe state epidemiologist most likely used which format to determine the cause of the disease? \nSelect and explain. \nA. Cross sectional study, B. Prospective study, C. Retrospective study, D. Case–control study', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Cross-sectional studies (Prevalence studies) \nThe simplest in concept and execution is the cross-sectional study. In this, a set of individuals are chosen who may be a\xa0representative sample of the general\xa0population or of people in a particular\xa0community or a sample of members of some\xa0special subgroup - school children, the\xa0armed forces, workers in a particular industry,\xa0etc. The measurements of exposure and\xa0effect are made at the same time providing\xa0information on the relationship between a\xa0disease and other variables of interest, as they\xa0exist at one point of time.\xa0Cross-sectional studies are relatively easy and economical to carry out.\xa0\nReference: Essentials of Preventive and Community Dentisitry, Soben Peter , 4th ed page no 57', 'role': 'assistant'}]