Major Histocompatibility Antigens Are

Major histocompatibility antigens are

A) glycoproteins found on the surface of most vertebrate animals.
B) antigens that provoke allergic reactions.
C) antigens attached to foreign invaders.
D) not really antigens, but rather antibodies produced to mask foreign antigens.
E) antigens that must be processed by cells called histiocytes in order to be recognized by the immune system.