The characteristics to the correct phylum matching is given below:
Explanation:
Organisms lack symmetry- Porifera. Poriferans such as sponges are without any symmetry, thus they are asymmetrical.
Organisms have specialized stinging cells -Cnidaria. Cnidaria such as <em>Hydra</em> possesses stinging cells or cnidocytes located around the mouth and tentacles of the <em>Hydra</em> and can kill prey with toxins.
Adult forms are sessile – Porifera. Adult sponges are sessile and spend their lives attached to a substrate.
Two types of body plan exist as polyp and medusa – Cnidaria. Cnidarians show two distinct body plans as polyp or stalk and medusa or bell. Polyps are non-motile and Medusa are motile.
Organisms obtain food by filtering water– Porifera. The water moves through the body of the poriferans to filter out food, absorb dissolved oxygen.
Phenomenon of alternation of generation is observed - Cnidaria. Alternation of generation is a type of life cycle which switches between two forms. In cnidarian, the asexual polyp alters with the sexual medusa.
