Here's why:

* Magma is molten rock found beneath the Earth's surface.

* Lava is molten rock that has erupted onto the Earth's surface.

Mid-ocean ridges are where new oceanic crust is formed. The process is driven by the movement of tectonic plates and the upwelling of magma from the Earth's mantle. This magma rises to the surface, cools, and solidifies, forming new oceanic crust.