Answer:
The correct answer would be A. crust.
The crust is the outermost layer of the earth which is composed of different types of rocks such as sedimentary, metamorphic, and igneous rocks.
It is completely solid and can be broadly classified into two types: continental crust and oceanic crust.
The thickness of the oceanic crust is about 5 km to 10 km. It is primarily composed of basalt, gabbro, and diabase.
The thickness of the continental crust is around 30 km to 50 km.
The crust forms lithosphere along with hard and upper mantle.
