Final answer:
Both Porifera and Cnidaria can reproduce asexually through budding. Cnidocytes, specialized stinging cells, are unique to Cnidaria. Porifera are asymmetrical, while Cnidaria have radial symmetry.
Step-by-step explanation:
The student is asking which feature is found in both the phyla Porifera and Cnidaria. The correct answer is: a) Asexual reproduction by budding. Both Porifera (sponges) and Cnidaria (such as jellyfish and corals) can reproduce asexually through the process of budding, where a new organism develops from an outgrowth or bud due to cell division at one particular site. This form of reproduction is common among many simple multicellular organisms. While Cnidaria also has a nerve net, this is not found in Porifera. Porifera, being very simple, do not have organized tissues such as a heart and blood vessels or a nerve net, and they are also neither bilaterally nor radially symmetrical, they are asymmetrical. Neither Porifera nor Cnidaria have bilateral symmetry; Cnidarians possess radial symmetry, whereas Porifera are asymmetrical with no symmetry.
Regarding cnidocytes, they are specialized cells found in phylum Cnidaria. These cells are used for stinging and capturing prey and are not found in Porifera.