Ctenophores are characterized by eight rows of cilia, which are used for locomotion. The cilia in each row are arranged to form a stack of combs, also called comb plates, or ctenes; thus the name ctenophore comes from the Greek, meaning "comb bearer.
A flame cell is a specialized excretory cell found in the simplest freshwater invertebrates, including flatworms (except the turbellarian order Acoela), rotifers and nemerteans; these are the simplest animals to have a dedicated excretory system. Flame cells function like a kidney, removing waste materials. Bundles of flame cells are called protonephridia.
The word nephridium applies in its strict sense only to the excretory organs of annelids, but it may usefully be extended to include the excretory organs of other phyla having similar characteristics. Annelids are segmented animals that typically contain a pair of nephridia on each segment.
Choanocytes are cells that line the interior of asconoid, syconoid and leuconoid body type sponges that contain a central flagellum, or undulipodia, surrounded by a collar of microvilli which are connected by a thin membrane. They make up Choanoderm, a type of cell layer found in sponges.
A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one giant secretory organelle or cnida (plural cnidae) that defines the phylum Cnidaria (corals, sea anemones, hydrae, jellyfish, etc.). Cnidae are used for prey capture and defense from predators.
So the correct option is 'A - (iii), B - (iv), C - (i), D - (v), E - (ii)'.