What causes the sea floor to spread apart at mid-ocean ranges?
Hot magma rises through the boundary at the mid-ocean ranges, creating new rock and pushing apart the plates


The waves in the ocean pull the plates away from each other. This happens at the mid-ocean ranges


The Earth's magnetic field is so strong it pushes apart the iron-filled rocks at the mid-ocean ranges


The Earth is growing in size (though we don't know why) and the mid-ocean ranges are where the crust has cracked to allow the Earth to get bigger.