Which of the followings indispensable amino acids are essential for human?

A. Pyrrolidine-2-carboxylic acid B. 4-hydroxyphenylalanine C. 2-Amino-4-methylpentanoic acid D. 2,6-Diammoniohexanoic acid

The indispensable amino acids are those amino acids that cannot be synthesised by the organism being considered and therefore must be supplied in its diet. The amino acids regarded as essential for humans are 2-Amino-4-methylpentanoic acid, 2,6-Diammoniohexanoic acid, etc. Hence, C and D both are indispensable amino acids and others are conditionally amino acids.