When a B-cell undergoes immunoglobulin class switching

Q. When a B-cell undergoes immunoglobulin class switching

A.            the variable region of the light chain changes, but its constant region remains the sam

B.            the variable region of the light chain remains the same, but its constant region changes

C.            the variable region of the heavy chain remains the same but its constant region changes

D.            both the variable and constant regions change

Answer: the variable region of the heavy chain remains the same but its constant region changes