You Culture Some B Cells and Find That They Are

You culture some B cells and find that they are expressing IgM , which reacts to sheep red blood cells. Later you test the media and find almost no IgM, but a lot of IgG. This IgG also reacts to sheep red blood cells. If you were to analyze the cells before and after the switch in antibody, you would see that the IgG producing B cells have a different _______ when compared to the IgM.

A) light chain variable region
B) heavy chain variable region
C) MHC I
D) light chain constant region
E) heavy chain constant region