What layer of the Earth lies between the crust and the core?

The layer of the Earth that lies between the crust and the core is the mantle. The mantle is a thick layer composed of silicate rocks that are rich in iron and magnesium. It extends nearly 2,900 kilometers deep down to the outer core and plays a crucial role in geological processes such as plate tectonics and convection currents, which are involved in the movement of the Earth's plates.

Understanding the mantle's position is essential, as it acts as a medium for heat transfer from the core to the crust. The temperature within the mantle increases with depth, which contributes to mantle convection. This movement is a driving force behind various geological activities, such as volcanic eruptions and earthquakes.

The other choices do not represent the correct layer that separates the crust from the core. The crust is the outermost layer of the Earth, while the core refers to the innermost layer, consisting of a solid inner core and a liquid outer core. The asthenosphere is a portion of the upper mantle that is semi-fluid and allows for the movement of tectonic plates but does not serve as the layer between the crust and core. Thus, the mantle is definitively the correct answer.