This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Demography and family planning, Subject name: Social & Preventive Medicine
Annual growth rate is 
Select and explain. 
A. Crude bih rate-Crude death rate, B. Crude death rate-Crude bih rate, C. Crude bih rate-Crude death rate x 100\/Crude bih rate, D. Crude bih rate-crude death rate x 100\/Mid bih rate population
A: Crude bih rate-Crude death rate
Answer: A: Crude bih rate-Crude death rate 
Explanation: When crude death rate is substracted from crude bih rate , the net residual is current annual growth rate, exclusive of migration. Population growth rates like railway trains are subject to momentum. They sta slowly and gains momentum, once in motion, it takes time to bring momentum under control. Reference: Park&;s textbook of preventive and social medicine, 23rd edition, pg no: 481