In the image above, the arrow is pointing to the layer of the earth that is made up of pieces called plates. which of the earth’s layers is the arrow pointing to?

I can't find the image, but the earth's plates that are involved in plate tectonics are composed of either oceanic crust which is mainly made of silica and magnesium and is more dense whereas the continental is mostly made up of the lighter silica and aluminum elements. So this is why the denser oceanic crust gets pushed under the lighter continental crust in the subduction zones. 

Ithink it’s true as the answer.