Read the following statements.

i) Collar cells are present in sponges. 

ii) Tapeworms have complete gut.

iii) Metagenesis is exhibited by dimorphic cnidarians.

iv) Bioluminescence is due to comb plates of ctenophores.

The correct ones of the above are

The digestive system in Platyhelminthes (Tape worms) has only a single opening to the outside of the body that serves as both mouth and anus, and is hence called incomplete.

In ctenophores, bioluminescence is caused by the activation of calcium-activated proteins named photoproteins in cells called photocytes, which are often confined to the meridional canals that underlie the eight comb rows.