In context of the given picture ,answer the following questions :

What are  A and B in  the above picture ?

A) Antigen binding site (B) Light chain 

The correct answer is Option (4) -A) Antigen binding site (B) Light 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 .

                               Structure of antibody