Metanephridial organs are common in

A) mollusks.
B) flatworms.
C) cnidarians.
D) sponges.
E) insects.

Metanephridial Organs

Metanephridial organs are excretory structures in some invertebrates, including annelids, that filter fluid directly from the animal's body cavity.

Mollusks

Invertebrates with a soft body, often protected by a hard shell, belonging to the phylum Mollusca, which includes snails, clams, and squids.

Common

Referring to something that is usual, typical, or shared among multiple entities or individuals.