Jerome had read about plate tectonics and the mid-Atlantic ridge. He investigated by reading further, learning that evidence existed to show volcanic activity was happening along the mid-Atlantic ridge. How do the pillow-shaped rocks found there provide evidence that volcanic activity is taking place? A. They form only when molten material cools slowly in warm water. B. They form only along subduction zones in the trenches of the Atlantic. C. They form only when lava erupts above the water when the air is cool. D. They form only when molten material hardens quickly in cold water.