Cephalization Is Clearly Adaptive for the Free-Living Planarians That Must

Cephalization is clearly adaptive for the free-living planarians that must locate their food; why would the parasitic flukes and tapeworms retain cephalization?

A) Those with separate sexes would need to locate one another when mating.
B) Parasitic infection is typically organ specific; parasites need to sense their location before attaching to a body structure.
C) Parasite life cycles require dispersal to new hosts, some parasites actively sense potential hosts and move toward them.
D) All of the above are reasonable hypotheses.