Final answer:
The Theory of Plate Tectonics explains that Earth's plates move or shift in relation to each other.
Step-by-step explanation:
The Theory of Plate Tectonics states that Earth's plates move or shift in relation to each other. These plates are made up of the lithosphere, which is the rigid outer shell of the Earth, and they float on the semi-fluid asthenosphere below. This movement is driven by convection currents in the mantle beneath the plates.
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