A Biologically Plausible Reason That Burrowing Earthworms Have Solid Segmental

A biologically plausible reason that burrowing earthworms have solid segmental walls but nonburrowing and parasitic annelids often have partial septa is

A) the segmentation was selected to enable better expansion during burrowing. Parasitic annelids do not burrow and the loss of. the ability to expand segments was not disadvantageous during their evolution.
B) the nonburrowing worms were primitive and had not yet developed full walls.
C) nonburrowing worms are halfway between roundworms and fully-segmented earthworms.
D) that it permits fragmentation and regeneration of body parts, which earthworms need because they are in a dangerous environment, but internal parasites do not need this.
E) None of the choices are correct.