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
Demographic bonus is due to: 
Select and explain. 
A. Decreased feility, B. Increased longevity, C. Both of the above, D. None of the above
A: Decreased feility
Answer: A: Decreased feility 
Explanation: The rapid decline in dependency ratios has been associated with rapid economic development. Demographic bonus is the period when dependency ratio declines because of decline in feility until it stas to rise again because of increasing longevity. Ref: Park, 22nd edition pg: 446