Which statement is correct about the characteristic features of immunoglobulins?

The statement that each class of immunoglobulin serves a unique function is correct. Immunoglobulins, or antibodies, are classified into several isotypes: IgG, IgA, IgM, IgE, and IgD, each with distinct roles in the immune response. For instance, IgG is primarily responsible for opsonization and neutralization of pathogens, while IgA is vital in mucosal immunity and is found in secretions like saliva and breast milk. IgM is effective in forming complexes with antigens early in the immune response, IgE is involved in allergic reactions and defense against parasites, and IgD often acts as a receptor on B cells. This diversity allows the immune system to respond effectively to a wide range of pathogens.

The other statements do not accurately reflect the characteristics of immunoglobulins. For example, it is not true that all immunoglobulins consist of identical heavy chains, as each class has a specific heavy chain type that defines its function and properties. Furthermore, while light chains play a role in antigen binding, heavy chains are also crucial to the structure and function of antibodies in recognition of antigens. Lastly, heavy chains are essential for classifying antibodies; they determine the isotype of the immun