Which of the following statements is true about hapten-

1. Haptens are small organic molecules that are antigenic but not immunogenic.They are not immunogenic because they cannot activate helper T cells. Failure of hapten to activate helper T cells is due to their inability to bind to MHC proteins; they cannot bind because they are not proteins and only proteins can be presented by MHC proteins. Moreover, haptens are univalent hence cannot activate B cells by themselves. 2. In general, only large molecules, infectious agents, or insoluble foreign matter can elicit an immune response in the body.