Question

harry hess compared seafloor spreading to what everyday object, and why was this comparison important?
a wheel, because the seafloor rotated in cycles
a zipper, because the seafloor opened and closed
a rolling pin, because it stretched continents
a conveyor belt, because new crust formed and pushed old crust away

Explanation:

Harry Hess compared seafloor - spreading to a conveyor belt. In seafloor - spreading, new oceanic crust is formed at mid - ocean ridges and pushes the older crust away, similar to how items are moved along by a conveyor belt.

Answer:

D. A conveyor belt, because new crust formed and pushed old crust away