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.

they use tree rings to figure out weather patters.