So all we know is that the student stated something ("<span>if plants are added to an indoor environment the air quality will improve
"). This is only a statement - it's not a test whether this statement is true yet.
So the correct answer is: it is a hypothesis.
</span>
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.
Because there has been no change in their environment, or/and no predators.
