What type of rock is primarily found in the Earth's mantle?

The correct answer identifies that the Earth's mantle primarily consists of soft, molten rock, which is known as magma in geological terms. The mantle is located between the Earth's crust and its outer core and is composed mainly of silicate minerals that can behave plastically over geological time. This plasticity allows for flowing and convection currents, which are essential for plate tectonics and volcanic activity.

While the mantle can contain solid rock, it is predominantly in a semi-solid state and can flow under high temperatures and pressures. This characteristic is crucial because it contributes to the movement of tectonic plates and the dynamic processes within the Earth.

Granite and basalt are specific types of igneous rocks found in the Earth's crust, not the mantle. Igneous rock also refers to a broader category that includes both basalt and granite, but it doesn't specifically address the composition of the mantle itself. By understanding these geological contexts, it becomes clear why the nature of the mantle is best described as soft, molten rock.