Question

sponges belog to which group?
a cnidaria
b mollusca
c porifera
d platyhelminthes
e annelida

Explanation:

Sponges are simple multicellular organisms. Cnidaria includes jellyfish and corals. Mollusca has snails and octopuses. Platyhelminthes are flatworms. Annelida are segmented worms like earthworms. Sponges are in Porifera as they have pores (ostia) for water flow.

Answer:

C. Porifera