Several Invertebrate Species, Such as Some Insect and Snail Species

Several invertebrate species, such as some insect and snail species, have mechanisms for increasing the diversity of immune recognition molecules that are expressed in an individual beyond the simple 'one gene encodes one protein' rule that applies to most genes in the genome. One of these mechanisms:

A) Uses a pair of enzymes that are related to the RAG recombinase enzymes found in vertebrates
B) Creates a library of complement proteins that function like vertebrate complement to promote phagocytosis of microbes by macrophages and neutrophils
C) Creates a clonally distributed set of immune recognition molecules by a process involving different DNA rearrangement events in each cell
D) Uses a mechanism in which a small number of cells expressing a few different proteins undergo massive proliferation to provide protective immunity
E) Resembles the V-D-J recombination process in vertebrates but occurs by differential RNA splicing rather than by DNA rearrangement