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 explosion is define as population growth rate of more than- _____ per year 
Select and explain. 
A. 2, B. 1.75, C. 1.8, D. 1.5
A: 2
Answer: A: 2 
Explanation: None