Final answer:
The Earth's mantle is a solid, rocky layer between the crust and the core. It is voluminous and behaves plastically, allowing for slow flow and deformation, which is important for tectonic activity.
Step-by-step explanation:
The Earth's mantle is best described as a solid, rocky layer located between the crust and the core (option a). Although it is a solid, it behaves in a plastic manner due to the high temperatures and pressures found at that depth, which allows it to deform and flow slowly. The mantle is the most voluminous of Earth's layers, extending from the base of the crust to a depth of about 2,900 kilometers. Its composition includes more iron, magnesium, and less aluminum and silicon compared to the crust, making it ultramafic. The density in the mantle increases with depth, ranging from about 3.5 g/cm³ near the crust to over 5 g/cm³ at its boundary with the core. Scientists have been able to study samples of mantle rock ejected from volcanoes, enhancing our understanding of its chemistry.The mantle's solid state is due to the balance between temperature and pressure inside the Earth. Despite being solid, the mantle's capacity to flow is crucial to the process of plate tectonics. The movement within the mantle is what ultimately drives the motion of the tectonic plates on the Earth's surface. As we go deeper into the Earth, we eventually reach the core, which, unlike the mantle, includes a liquid outer core and a solid inner core composed mainly of iron and nickel.Conclusion:In summary, the correct answer to what best describes the Earth's mantle is a solid, rocky layer that lies between the Earth's crust and core, with a capacity to flexibly deform over geological time scales. Understanding the Earth's mantle is crucial to our knowledge of geological and tectonic processes.