Antibody molecule has:

Four peptide chain

The correct answer is Option (3) - Four peptide chain

The B-lymphocytes produce an army of proteins in response to pathogens into our blood to fight with them. These proteins are called antibodies. The T-cells themselves do not secrete antibodies but help B cells to produce them. Each antibody molecule has four peptide chains, two small called light chains and two longer called heavy chains. Hence, an antibody is represented as H2 L2 . Different types of antibodies are produced in our body. IgA, IgM, IgE, IgG , IgD are antibodies . Because these antibodies are found in the blood, the response is also called as humoral immune response .