Question

which of the following statements describes how tectonic plates move?
a. they move slowly on top of the mantle.
b. they move from the mantle to the inner core.
c. they move from the crust to the core.
d. they move from the inner core to the outer core.

Explanation:

Tectonic plates are part of the Earth's lithosphere. The lithosphere (which includes the crust and upper - most rigid part of the mantle) "floats" on the more ductile asthenosphere (a part of the mantle). Tectonic plates move slowly over the mantle due to convection currents in the mantle.

• Option B: Tectonic plates are not moving from the mantle to the inner core. The inner core is solid and at a much deeper layer, and tectonic plates are part of the lithosphere (crust and upper mantle).
• Option C: Tectonic plates are part of the crust (and upper mantle) and do not move from the crust to the core. The core is a separate, deeper - lying layer.
• Option D: The movement of tectonic plates has nothing to do with the movement from the inner core to the outer core. The inner and outer core are deep within the Earth, and tectonic plates are on the surface (in terms of their position relative to the core).

Answer:

A. They move slowly on top of the mantle.