Final answer:
The base of Earth's crust is known as the Moho, which is the boundary between the crust and the mantle. It is not the mesosphere, geosphere, outer core, or inner core. Seismic studies have been instrumental in revealing the Earth's interior structure, including the crust, mantle, and core.
Step-by-step explanation:
The base of Earth's crust is generally identified as the boundary known as the Moho, or the Mohorovičić discontinuity. This boundary marks the transition from the Earth's crust to the underlying mantle. The other options provided such as the mesosphere, geosphere, outer core, and inner core, are not located at the base of the Earth's crust. The mantle lies directly beneath the crust and is the largest portion of Earth's volume, consisting of a solid that can deform plastically at high temperatures and pressures. The outer core and inner core are located even deeper, making up the central part of the Earth, with the outer core being liquid and the inner core being solid, predominantly made of iron and nickel.Seismic studies have been crucial in understanding the Earth's interior structure, revealing the layered composition that includes the crust, mantle, and core. Understanding this structure helps us comprehend phenomena such as the generation of Earth's magnetic field and the mechanisms driving plate tectonics, which are responsible for earthquakes and volcanic eruptions.