The correct option is
D OphiothrixA)
Leucosolenia is a poriferan which is a protostome.
B) Dentalium is a mollusc which is a protostome.
C) Dugesia is a flatworm belonging to platyhelminthes and is protostome.
D) Ophiothrix is an echinoderm. All echinoderms are deuterostomes.
So the correct answer is 'Ophiothrix'.