What is a distinguishing visible feature of each stage of the cell cycle?

one of the visible feature is that the DNA in a cell is replicating then the most important is that they are splitting of getting divided and form into two identical cells.

Explanation:

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.

i believe your answer would be c.. : )