The Brainliest Answer!
a ) jelly fish , mushroom , sea pen are acoelomate bodies .

b ) notochord are the place for muscles to  attach for easy movement and locomotion .

c ) chordates are triploblastic , coelomate , dorsal ( stomach side ) and they have also notochord. kidney like organs are present .

2 5 2
Is mushroom an animal?
mushrooms are not in plant ( photosynthesis is not posses ) and not in the animals ( cell wall is present ) .
A)animals without a coelom are:Porifera,Coelenterata(Cnidaria),jellyfish

The notochord is the defining structure of the chordates, and has essential roles in vertebrate development. It serves as a source of midline signals that pattern surrounding tissues and as a major skeletal element of the developing embryo.

C)all chordates posses the following features:
i)have a notochord
ii)have a dorsal nerve
iii)are coelomate
iv)have paired gill pouches