Read the following statements.

(a) Metagenesis is observed in Helminths.

(b) Echinoderms are triploblastic and coelomate animals.

(c) Round worms have organ-system level of body organization.

(d) Comb plates present in ctenophores help in digestion.

(e) Water vascular system is characteristic of Echinoderms.

Choose the correct answer from the options given below.

To determine the correct statements, let us analyze each of the given statements step-by-step:

Statement (a): Metagenesis is observed in Helminths.
Metagenesis, also known as alternation of generations (between asexual polyp forms and sexual medusa forms), is a characteristic feature of certain Cnidarians (Coelenterates), such as Obelia. It is not observed in Helminths (Platyhelminthes or Aschelminthes). Therefore, statement (a) is incorrect.

Statement (b): Echinoderms are triploblastic and coelomate animals.
Echinoderms are multicellular animals that possess three embryonic germ layers (ectoderm, mesoderm, and endoderm), making them triploblastic. They also possess a true coelom (body cavity lined by mesoderm), making them coelomate. Therefore, statement (b) is correct.

Statement (c): Round worms have organ-system level of body organization.
Roundworms belong to the phylum Aschelminthes (Nematoda). They exhibit an organ-system level of body organization, where tissues are grouped together to form functional organs, which in turn associate to form organ systems. Therefore, statement (c) is correct.

Statement (d): Comb plates present in ctenophores help in digestion.
Ctenophores (commonly known as comb jellies) possess eight external rows of ciliated comb plates. These comb plates are used primarily for locomotion, not digestion. Digestion in ctenophores is both extracellular and intracellular. Therefore, statement (d) is incorrect.

Statement (e): Water vascular system is characteristic of Echinoderms.
The water vascular system (or ambulacral system) is a distinctive hydrostatic system unique to the phylum Echinodermata. It helps in locomotion, capture and transport of food, and respiration. Therefore, statement (e) is correct.

Comparing our analysis with the given options, we find that statements (b), (c), and (e) are correct, which corresponds to the fourth option.