This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
Case control study is- 
Select and explain. 
A. Prospective, B. Retrospective, C. Cross sectional, D. None of the above
B: Retrospective
Answer: B: Retrospective 
Explanation: .<p>case control studies are usually retrospective studies that proceed from an effect to a cause.</p><p>ref:park&;s textbook of preventive and social medicine,22 nd edition ,pg no 131</p>