Organisms under phylum 'Ctenophora' are also known as (a) Roundworms (b) Comb jellies (c) Ctenoplana (d) Flatworms

Ctenophora is a phylum in the animal kingdom, consisting primarily of marine species. These organisms are characterized by their unique combs made of cilia, which help them to move through the water.

Now that we have an understanding of the key characteristics of Ctenophora, it is time to determine which of the provided options represents the common name for these organisms. (a) Roundworms: Roundworms are also known as nematodes and belong to the phylum Nematoda, not Ctenophora. So, this option is incorrect. (b) Comb jellies: Comb jellies are the common name for organisms in the phylum Ctenophora. They are named after their unique combs that help them move, as mentioned in Step 1. So, this option is the correct answer. (c) Ctenoplana: Ctenoplana is a genus within the phylum Ctenophora, not the common name for the entire phylum. So, this option is incorrect. (d) Flatworms: Flatworms are members of the phylum Platyhelminthes, not Ctenophora. So, this option is incorrect.

After reviewing each option, we can conclude that the correct answer is (b) Comb jellies, as they are the common name for organisms within the phylum Ctenophora.