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: Social & Preventive Medicine
[{'content': 'Which of the following also known as prevalence study \nSelect and explain. \nA. Cohort study, B. Case control study, C. Cross - sectional study, D. Ecological study', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]