The correct response is: Minerals from the crust dissolve in water that is superheated by magma, and the minerals are deposited on the ocean floor as the water cools.
At divergent ocean boundaries, tectonic plates move apart, allowing seawater to enter the fractures and come into contact with the hot magma beneath. This superheating can dissolve minerals from the crust, and as the heated water rises and cools, it can precipitate these minerals, forming deposits on the ocean floor.