To determine which of the statements about Insulin are correct, let's examine each statement individually: [A] Insulin is a globular protein consisting of 51 Amino acids. This statement is correct. Insulin is indeed a globular protein, and the most common form of human insulin consists of 51 amino acids. [B] Insulin is constituted of 3 polypeptide chains linked together. This statement is incorrect. Insulin is made up of 2 polypeptide chains, not 3 . The correct number of polypeptide chains in insulin is two. [C] Insulin is constituted of 2 polypeptide chains linked together by disulphide bonds. This statement is correct. Insulin has two polypeptide chains, the A-chain and the B-chain, which are linked together by disulphide bonds. [D] The 3 polypeptide chains in Insulin are linked together by Hydrogen bonding. This statement is incorrect for two reasons. First, insulin does not have 3 polypeptide chains, and second, the chains are linked by disulphide bonds, not hydrogen bonds. From this analysis, we can see that the correct statements are [A] and [C]. Therefore, the correct option is: Option B [A] & [C]