This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiological Study, Subject name: Social & Preventive Medicine
[{'content': 'Cause to effect progression is seen in all EXCEPT: \nSelect and explain. \nA. Case control study, B. Ecological study, C. Cohort study, D. Randomized control trial', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ANSWER: (A) Case control studyREF: Park 20th edition page 67 Repeat in December 2011Cause to effect (disease) = prospective study (cohort study)Effect (disease) to cause = retrospective study (case control study)RCT and ecological studies are also prospective studies', 'role': 'assistant'}]