Lysine and tryptophan are:
a. proteins
b. non-essential amino acids
c. essential amino acids
d. aromatic amino acids.
Essential amino acids are the amino acids that cannot be synthesised in the human body and should be supplemented in the diet.
Lysine helps promote antibody formation, enzyme and hormone production, fixation and development of calcium in bones.
Tryptophan helps in the formation of serotonin and vitamin B3.
Hence, the answer is option (c) essential amino acids.