The classic experiment using isolated cells from two species of sponges provided evidence that:
cell adhesion molecules are species specific.
cell adhesion molecules are non-specific.
sponge cells have cell adhesion molecules.
sponge cells posses an extracellular matrix.

answer: the answer is b

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.