<prompt> Answer this question truthfullyAmong the immunoglobulins, which one has the highest avidity?  <response>: <reason> The immunoglobulin that has the highest avidity is IgM. Avidity refers to the strength of binding between an antibody and its antigen. IgM is a pentameric antibody that has ten antigen-binding sites, which allows it to bind to multiple epitopes on an antigen simultaneously. This results in a high-avidity binding, which is important for the effective clearance of pathogens. In contrast, other immunoglobulins, such as IgG, have lower avidity because they are monomeric and have fewer antigen-binding sites. However, IgG antibodies have a higher affinity for antigens, which means they bind more tightly to a single epitope. Both high-avidity binding and high-affinity binding are important for the effectiveness of the immune response. 