Which of the following options consist of non-essential amino acids only?
(a) Valine, leucine, glycine, alanine
(b) Glycine, serine, proline, glutamic acid
(c) Proline, aspartic acid, glutamic acid, methionine
(d) Cysteine, tyrosine, alanine, isoleucine
(b) Non-essential amino acids are those amino acids which can be synthesized by human body from raw materials. Glycine, serine, proline, glutamic acid all are non-essential amino acids.