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Sponges, members of the Porifera, might be the simplest multicellular animals on Earth. They do not have any tissues, organs, or organ systems. In order for sponges to have evolved, what MUST have happened first?
A)
the organization of cells into groups
B)
symbiotic relationships among various cells
Eliminate
C)
the evolution of cells with nuclei and organelles

D)
the development of the cell wall as a protective mechanism