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: Pediatrics
Extremely low birth weight (ELBW) is called when birth weight is less than _____________ 
Select and explain. 
A. 2 kg, B. 2.5 kg, C. 1 kg, D. 1.5 kg
C: 1 kg
Answer: C: 1 kg 
Explanation: Low Birth weight (LBW) : Birth weight < 2.5kg
Very low birth weight (VLBW) : Birth weight < 1.5 Kg
Extremely low birth weight ( ELBW) : Birth weight < 1 Kg