This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
[{'content': 'Which of the following is best in studying the decline in percentage of alcohol usage in men ad women over several years? \nSelect and explain. \nA. Pie cha, B. Histogram, C. Frequency polygon, D. Line diagram', 'role': 'user'}, {'content': 'Answer: D \nExplanation: .', 'role': 'assistant'}]