The ability of one person to produce over a million different antibody molecules does not require over a million different genes; rather,this wide range of antibody production is due to

A)alternative splicing of exons after transcription.
B)increased rate of mutation in the RNA molecules.
C)DNA rearrangements.
D)rearrangements of cytosolic proteins in the thymus cells.
E)crossing over between the light and heavy chains of each antibody molecule during meiosis I.