Answer:
The stretching lithosphere is pushed up as the plates move apart.
Explanation:
Mid-ocean ridges are basically underwater mountains that are created with the help of lava convection (which causes the rising of plates) and the diverging (the pulling away) of tectonic plates. This is also how ocean floor spreading happens.
I know that mountains are formed by the converging of tectonic plates, but ocean ridges are NOT created like this.
Hope this helps :)