Ocean spreading centers are highlands on the ocean floor, sometimes referred to as submarine mountains. Oceanic crust worldwide is about the same thickness so isostasy would suggest the ocean floor should be as flat as Kansas.
Which of the following statements best describes the origin of these submarine mountains?
a. The ridges represent upwelling zones from the core which produces a bulge at the earth's surface.
b. The ridges are sites of young volcanos that produce high topography on the sea floor, like Hawaii.
c. The mantle beneath the ridges remains hot for millions of years producing an elevated region along the ridge axis because hot rocks are lower density than cold rocks.
d. Compression at the ridges produce local uplift along the ridge axis.

The mid-oceanic ridges are the submarine mountains that are formed in a divergent plate boundary. In this region, the oceanic crust gradually rises due to the movement of the magma towards the surface. This movement of magma upward is due to the formation of convection current in the mantle, where these currents are generated because of the heat energy provided from the interior of the earth.

These are the region, where the temperature is extremely high and the rocks are in the form of liquid (magma) and hot rocks are less denser than the cold rocks, so they move upward. This motion of magma upward and erupting on the seafloor leads to the uprising of the oceanic crust.

Thus, the correct answer is option (C).