Mutations are important for evolution because they

Answer

C. They are source of new genetic variation

Explanation

Mutation result in genetic changes allowing species to develop new traits because the DNA changes thus affecting how the living organism will behave, look  and adjust to physiology  processes. Through mutation, evolution has been achieved because living things can survive as they fit into new environment with new traits acquired through mutation.

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.