This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: obstetrics,pediatrics and geriatrics, Subject name: Social & Preventive Medicine
[{'content': 'Extremely low bih weight baby is less than - \nSelect and explain. \nA. 1 kg, B. 1.5 kg, C. 2 kg, D. 2.5 kg', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Extremely low bih weight is bih weight less than 1kg Very low bih weight is bih weight less than1.5 kg Low bih weight is less than 2.5 kg Reference text book of obstetrics by Sheila Balakrishnan 2nd edition pg 548', 'role': 'assistant'}]