A) a variable and constant region on each polypeptide chain
B) two identical heavy polypeptide chains
C) two identical light polypeptide chains
D) disulfide bonds between polypeptide chains
E) four antigen binding sites

A) possess MHC antigens for recognizing self
B) have membrane receptors that recognize foreign antigens
C) gain tolerance to self by destruction of lymphocytes that could react against self
D) develop into clones of B and T cells with extreme variations of specificity
E) All of these choices are correct.

A) marker
B) antibody
C) hapten
D) antigen
E) PAMP