Answer:
notochord, a dorsal hollow nerve cord and pharyngeal slits.
Density = mass / volume
Plug in the values for mass and volume
Density = 1,800g / 300cm^3
Density = 6 g/cm^3
The correct answer is option A, that is, Phylum Porifera.
The species of Phylum Porifera are aquatic, that is, mostly marine. They exhibit cellular grade of the body, they are diploblastic animals with asymmetrical symmetry. They lack body cavity and exhibits a holozoic mode of nutrition with intracellular digestion.
They lack circulatory and nervous system and possess the tendency to regenerate their parts of the body. The organisms in phylum Porifera exhibits both asexual and sexual mode of reproduction.
Breathing is an essential part of the works of the body. If you go a long time without breathing, you’ll die. The reason why you can go a long time without eating is because your body stores the fat to keep you going. Breathing is kind of the building block of the body.
I think it's first quater, hope that helped!