Which among the following is an essential amino acid?

Valine

The correct answer is Option (3) → Valine.

Essential amino acids are those that cannot be synthesized by the human body and must be obtained from the diet.

Valine is one of the essential amino acids, meaning it must be consumed in food sources like meat, dairy, and legumes.

The other amino acids listed—Glycine, Alanine, and Serine—are non-essential amino acids, meaning the body can synthesize them on its own.

Summary:

Among the options, Valine is the essential amino acid.