Oceanic crust
a. has the same composition as continental crust.
b. is the same age as continental crust.
c. has not been sampled directly because it is too deep beneath the ocean.
d. is covered by a thin blanket of sediment that thickens away from the ridge axis.

D - is covered by a thin blanket of sediment that thickens away from the ridge axis.

Explanation: Oceanic Crust is the outermost layer of the lithosphere tectonic plates.

It is formed at sea level with dense rock which form distinct layers.

The oceanic crust is about 6km in thickness and it is composed of basaltic rock overlain by sediments and it is found under the ocean.

Oceanic crust is divided into upper oceanic crust and lower oceanic crust.

since there isn't any suggested answers i will give you the reason and hopefully you can figure it

south africa, or rather all of africa, has not been in the location in which it is nowadays throughout the geological past. after the super-continent pangaea started to break apart, gondwanaland, in which was africa, moved further south, and parts of it came to be very close to the south pole. because the climate in this part of the world is very cold due to the very dispersed sun rays in there, what is now south africa, started to freeze, and the conditions were right for the formation of glaciers. the glaciers existed up until the period when gondwanaland started to break apart and what is now africa started to move towards north, sp it warmed up and the glaciers melted.