To determine which amino acid among the given options is non-essential, we need to understand the difference between essential and non-essential amino acids.
Essential Amino Acids: These cannot be synthesized by the body and must be obtained from the diet. Examples include valine, leucine, and lysine.
Non-Essential Amino Acids: These can be synthesized by the body, making it unnecessary to obtain them through diet. An example is alanine.
Let's evaluate each option:
From the evaluation, Alanine is identified as the non-essential amino acid, as it can be synthesized by the body. Hence, the correct answer is alanine.