What is the thickness of the mantle, in kilometers?

The mantle of the Earth is approximately 2,900 kilometers thick, making it the largest layer of the Earth's interior, situated between the crust and the outer core. This significant thickness can be attributed to the mantle’s composition, which is rich in silicate minerals and is responsible for many geological processes, including plate tectonics and mantle convection. The other options provided, while they suggest various thicknesses, do not accurately reflect the current geological understanding of the mantle’s extent beneath the Earth's surface. Thus, the correct answer reflects a well-established estimation of the mantle's total thickness.