Which of the following is an essential amino acid?
Threonine
Glutamic acid
Alanine
Serine
As we have learnt,
Essential amino acids cannot be synthesised in the body and must be taken in food.
The essential amino acids are arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine
Theronine is the only essential amino acid among the given.
Hence, the correct answer is Option (1)