Question

Which answer explains why plate B is moving underneath plate A

A. Plate B is more dense than plate A because it is composed of oceanic crust


B. Plate A is more dense than plate B because it is composed of oceanic crust


C. plate B is more dense than plate A because it is composed of continental crust


D. Plate A is more dense than plate B because it is composed of continental crust

Answer 1

A.

Step-by-step explanation:

Earth is composed of different layers and one layer moves over another due to differences in the densities.

According to the physics of density, a substance having less density floats over a higher density substance. The oceanic crust has more density than the continental crust that is why continental crust float over oceanic crust.

So in the given example, plate B is moving below the plate A, it means plate B is more dense than plate A because plate B is composed of oceanic crust . For example : continents float over the asthenosphere (a layer below the lithosphere).

Hence, the correct answer is "A ".