The correct option is D Platyhelminthes
Flatworms are bilaterally symmetrical, triploblastic and acoelomate animals with organ level of organisation. Members of phylum aschelminthes are triploblastic, bilaterally symmetrical and pseudocoelomates. Annelids are triploblastic, bilaterally symmetrical and coelomates. Animals in phylum ctenophora are radially symmetrical and diploblastic.