Please explain Which of the following statements is correct? A. Individuals with mutations in the AID enzyme are able to produce antibodies that cross the placenta. B. Individuals with mutations in the AID enzyme are able to produce antibodies that activate complement. C. The AID enzyme targets recombinase signal sequences (RSSs) during the process of isotype switching? D. Isotype switching occurs prior to a B cell's exposure to foreign antigen..