Identify me. a. I am diploblastic & acoelomate. Which phylum do I belong to

a. I am diploblastic & acoelomate. Which phylum do I belong to?

b. My body is radially symmetrical. Water vascular system is present in my body. I am referred as fish though I am not. What is my name?

c. I live in your small intestine. Pseudocoelom is present in my thread like body. In which phylum will you include me?

d. Though I am multicellular, there are no tissues in my body. What is the name of my phylum?