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
Population coverage of primary health center 
Select and explain. 
A. 20,000 in plain area, B. 10,000 in tribal area, C. 30,000 in tribal area, D. 30,000 in plain area
D: 30,000 in plain area
Answer: D: 30,000 in plain area 
Explanation: None