Why is cysteine considered essential in preterm infants?

• A. Because the enzyme necessary for cysteine synthesis via the methionine trans-sulfuration pathway is not present in adequate amounts in preterm infants
• B. Because cysteine is not required by preterm infants due to maternal supply
• C. Because cysteine can be synthesized from methionine in preterm infants but is insufficient
• D. Because cysteine deficiency is a universal newborn deficiency

Answer: (A)