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
[{'content': 'Bih rate is \nSelect and explain. \nA. Live bih X 1000\\/ mid yr. Population, B. Bih X 1000\\/ mid yr population, C. Live bih X 10000\\/ mid yr. Population, D. Live bih X 10000\\/Population of reproductive age group (15-45)', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Bih rate = number of live bihs during the year X 1000/ estimated mid year population. Unsatisfactory measure of feility because the total population is not exposed to child bearing. Reference : Park&;s textbook of preventive and social medicine, 23rd edition, pg no: 488', 'role': 'assistant'}]