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': 'Early expanding stage is denoted by \nSelect and explain. \nA. Decreased birth rate and Decreased death rate, B. Increased birth rate and Increased death rate, C. Unchanged birth rate and Decreased death rate, D. Decreased birth rate and Increased death rate', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]