Final answer:
The classification for an infant with an extremely low birth weight (ELBW) is a weight of less than 1000 g.
Step-by-step explanation:
The classification for an infant with an extremely low birth weight (ELBW) is a weight of less than 1000 g (option B). Extremely low birth weight is a designation for infants who weigh less than 1000 grams or 2.2 pounds at birth. This classification is important for diagnostic and treatment purposes as ELBW infants are at higher risk for complications and require specialized care.