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
Crude bih rate is the simplest measure of feility because the denominator is ? 
Select and explain. 
A. Total population, B. Mid-year population, C. Pre-term bihs, D. Live bih
B: Mid-year population
Answer: B: Mid-year population 
Explanation: Ans. is 'b' i.e., Mid-year population