What process is occurring at number 4 and how does it create new crust?

Explanation:
This process occurs at a divergent plate boundary where two oceanic plates move away from each other. As the plates pull apart, magma from the Earth's mantle rises to fill the gap. This magma then cools and solidifies, forming new oceanic crust. This continuous creation of new crust pushes the older crust away from the boundary, leading to the expansion of the ocean floor and the formation of a mid-ocean ridge.