Of all the major phyla the one that does not have a proper nervous system is the Porifera.
Answer: Option B
Step-by-step explanation:
Any organism requires a nervous system to communicate between the activity center that is the brain. The nerves serve as communication vehicles between the brain and other parts of the body .
The phylum porifera majorly contains the sponges which do not have any nerve or brain cells . Their major communication between cell to cell is the circulation of water and the ejection of waste that occurs from the inside to the outside.