Which of the following is an essential amino acid containing a sulphur atom?

Step-by-step solution

Amino acids can be classified based on their side chains and their essentiality. Among the given options, cysteine and methionine are sulphur-containing amino acids, whereas serine and threonine contain hydroxyl ( -OH ) groups. Further, amino acids that cannot be synthesised in the body and must be obtained through diet are called essential amino acids. Methionine is an essential amino acid, while cysteine is a non-essential amino acid. Therefore, methionine is the only essential amino acid containing a sulphur ato