The figure shows four animals (a), (b), (c) and (d). Select the correct answer with respect to a common characteristic of two of these animals.
(a) and (d) have cnidoblasts for self-defence
(c) and (d) have a true coelom
(a) and (d) respire mainly through body wall
(b) and (c) show radial symmetry
Figures C and D show octopus (molluscs)and a scorpion (arthropod) respectively. They both have true coeloms. Platyhelminth (tapeworm) is depicted in Figure A, and Aurelia is depicted in Figure B depicts a cnidarian. Scorpion uses its book lungs for breathing. On the octopus, there is bilateral symmetry. There are no cnidoblasts for self-defense in tapeworms.