A) IgM
B) IgA
C) IgE
D) IgD
E) IgG

11) ____Has the ability to cross the placenta.
12) ____In its dimerized form it protects mucosal barriers.
13) ____Involved in type I hypersensitivities.
14) ____B cell receptor.
15) ____First to peak during a primary immune response.