Answer:
The evidence that originally supported Hess's idea of seafloor spreading was that the younger rocks are closer to mid-ocean ridges.
Explanation:
A is correct because Hess noticed that the rocks that are closer to the mid-ocean ridges are younger, and as their distance from the mid-ocean ridge increased, their age increased as well, thus giving him a clue that the seafloor is spreading.
B is not correct because Hess never managed to examine the deep-sea trenches.
C is not correct because Hess didn't have the means to be that close (in water) to a mid-ocean ridge where the new crust is formed so that he can witness it, and this was mainly due to the lack of proper equipment.
D is not correct because magnetic stripes indicate the positions of the poles throughout the geological past.
