This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Screening, Subject name: Social & Preventive Medicine
[{'content': 'Which is most economical and best screening \nSelect and explain. \nA. Mass screening, B. High risk screening, C. Multiphasis screening, D. Any of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref:Parks 23rd edition pg 137 High-risk or selective screening : Screening will be most productive if applied selectively to high-risk groups, the groups defined on the basis of epidemiological research. Types of screening : Mass screening. High-risk or selective screening. Multi-phasic screening.', 'role': 'assistant'}]