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': 'Validity of an indicator means - \nSelect and explain. \nA. It should actually measure what it is supposed to measure, B. The answer should be same if measured by different persons in similar circumstances, C. Indicators should reflect changes in the situation concerned -, D. Indicators should have ability to obtain data needed', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]