Photosynthesis can be defined as the process by which green plants manufacture their food. Photosynthesis is important not only to plants themselves but also to animals, which depend on plants for food.
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.
It gives you a generic understanding of how the sequence of events will go.
The researcher could look for the presence of proteins, because viruses have a envelope (capsid) composed of proteins that involve their genetic material. The capsid may have a helical or icosahedral structure and is extremely regular. Viroids cannot synthesize any type of protein, so differentiation is possible.