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': 'Power of a study can be increased by - \nSelect and explain. \nA. Increasing α error, B. Decreasing β-error, C. Decreasing α error, D. Increasing β error', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]