Hess’ seafloor spreading hypothesis primarily explains the idea that the ocean floor is continually being created and pushed away from the mid-ocean ridges. Among the options provided, the most relevant response to Hess’ hypothesis is:
Fossils found on the ocean floor are much younger than those on continents.
This is because seafloor spreading suggests that new oceanic crust is formed at mid-ocean ridges and older crust is pushed further away, leading to younger geological features and fossils on the ocean floor compared to those found on the continents.