Which of the following correctly describes seafloor spreading?

a. new oceanic crust is formed at deep-sea trenches, pushed away from the trench, and destroyed at midocean ridges.
b. new oceanic crust is formed at midocean ridges, pushed away from the ridge, and destroyed at deep-sea trenches.
c. new oceanic crust is formed at seamounts and spreads outward in all directions.
d. new oceanic crust is formed in the middle of tectonic plates and then spreads outward in bands.