Answer:
The correct answer is - A. through the use of earthquake waves.
Step-by-step explanation:
The interior of the earth can not be studied or seen by digging the hole, for that scientist normally use the movement of seismic waves, from earthquakes or nuclear test explosions, are reflected, slow down, sped up bent by passing through the different layers.
Waves behave differently as they move in different layers and their material helps scientists to learn and study the layers and their constituents. It explains that the Earth's interior has a series of concentric shells, with a thin outer crust, a mantle, a liquid outer core, and a solid inner core.