The correct answer is option C
The formation of new layer of floor in the ocean is called seafloor spreading. It is a geological process which is caused due to the volcanic activity.
In this the new oceanic crust is formed due to the volcanic activity and the older rocks move away from the mid oceanic ridge.
The new layer formed lies in the middle of the ocean and the older rocks or floor moves aside.
This process occurs due to the divergent plates and the gap between them increases forming new oceanic ridge.