Question

1. sea floor spreading is _______.

when underwater mountains become flat to make the oceans bigger
when valleys in the middle of the ocean swallow up old land that was under the ocean
when new land pushes up from the middle of the earth and pushes apart the land under the ocean
when old land is pulled back under the surface of the earth in the middle of the ocean

Explanation:

Sea floor spreading is a geological process where magma rises from the Earth's mantle at mid-ocean ridges, creating new oceanic crust. This new crust pushes the existing oceanic crust away from the ridge, spreading the seafloor.

Answer:

when new land pushes up from the middle of the Earth and pushes apart the land under the ocean