Earthworms Possess Both Male and Female Organs on Separate Segments;

Earthworms possess both male and female organs on separate segments; thus, mating consists of "parallel parking" in opposite directions and cross-fertilizing. Given this, which of the following is (are) true?

A) This is evidence of a primitive state that is generally less efficient than separate sexes.
B) This is primarily to allow them to self-fertilize if no other worm is in their sector of the soil.
C) This is an advantage since they can mate with any other earthworm of the same species that they encounter.
D) Maintaining any system not clearly male or female is disadvantageous; the earthworm is trapped in an evolutionary dead end.