I believe the answer is C. The nearer you grow to the new ocean ridge to younger the crust gets, and the overlying sediment grows thin. The crust is younger because of the rising and cooling mantle creating new crust.
Option C, The oldest crust is closest to the mid-ocean ridge.
Explanation:
The oldest crust of sea floor is somewhere around 300 million years old. Mid-ocean ridges are the location where these crust are created and then they start moving away from each other. The continents are continuously moving away from each other since ages, hence it is for sure that the old crust would be very far away from mid-ocean ridges.
