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
The spindle-shaped Age pyramid denotes? 
Select and explain. 
A. Developing country, B. Underdeveloped country, C. Middle east country, D. Developed country
D: Developed country
Answer: D: Developed country 
Explanation: None