Registered Dietitian

Answer: B - Alanine, proline, and cysteine are not considered to be essential amino acids for adults, but may be essential for children for growth and development. The remaining listed amino acids (leucine, lysine, tryptophan, histidine, arginine, threonine, phenylalanine, valine, and methionine) are essential for both adults and children, since they are needed for life, and cannot be produced by the human body.