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': 'The study of first choice for the assessment of an unknown or new disease when there is no etiological hypothesis is ___: \nSelect and explain. \nA. Cohort study., B. Randomized clinical trials., C. Ecological studies., D. Descriptive studies.', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Descriptive studies:\n→ Descriptive studies are used to describe a disease of unknown etiology.\nSteps of descriptive studies :\n\nDefining the population to be studied.\nDefining the disease under study.\nDescribing the disease by\n\na. Time\nb. Place\nc. Person\n\nMeasurement of disease.\nComparing with known indices.\nFormulation of an aetiological hypothesis', 'role': 'assistant'}]