Embryonic stem cells,
Tissue-specific stem cells.
Answer:
B. Allows for specialized regions with specialized functions
Explanation:
Where the complete digestive system has different specialized regions to perform specialized functions, the gastrovascular cavity is the primary organ of digestion and circulation in two major animal phyla: the Cnidaria (including jellyfish and corals) and Platyhelminthes (flatworms).
That they both had nearly the same hypothesis
The answer should be the contraction of muscles.
Hope this helps mate.