Amino acids mostly contain following elements:

Explanation

Amino acids, the building blocks of proteins, are primarily composed of carbon, nitrogen, oxygen, and hydrogen. These elements form the backbone of the amino acid structure, with nitrogen being present in the amino group of each amino acid. Although some amino acids contain sulphur, it is not a common component in all amino acids, distinguishing them from the primary elements listed in Option A. Therefore, Options B, C, and D are incorrect as they include sulphur, which is not a primary element in all amino acids, and some options omit nitrogen and hydrogen, which are essential components.