Secondary radial symmetry is found in

Water vascular system (ambulacral system) is typically found in

Which phylum is characterized by the presence of a water vascular system?

An enterocoelomate invertebrate group is

Which of the following is a characteristic feature of the phylum $Echinodermata$?

Water vascular system is the characteristic of which group of the following:
$(a)$ Porifera $(b)$ Ctenophora $(c)$ Echinodermata $(d)$ Chordata