The correct option is D Hexacanth
Taenia is a genus of tapeworms. The larvae of Taenia are hexacanth, meaning they have six posterior hooks on the scolex. This is present in ripe proglottids, covered by chromosphere, which is a shell-like structure.
Miracidium is the free-swimming ciliated larva in which parasitic fluke passes from the egg to its first host.
Bladderworm is the encysted larvae of the tapeworm.
Thus, the correct answer is option B.