The Canal system is a unique feature of which phylum?
 

Concept: The water canal system is the basic system in the simplest animal that help an animal in respiration, excretion and digestion.
Sponges are the simplest animals and have a water canal system, in which water flows through the canal of sponges and brings nutrition to them.
Porifera includes primitive porous multicellular animals having a cellular level of organisation. A common name for Porifera is sponges. Sponges have a water canal system. They have four types of canal systems that are the ascon type, sycon type, leucon type, and rhagon type. E.g., Sycon. 
Hence, option B is the correct answer.