Question

which statement best describes the theory of plate tectonics?
plates sometimes move closer to one another.
sections of earth that shift are part of earth’s asthenosphere.
sections of earth’s continents are in slow, constant movement.
parts of the ocean floor move as they are carried by rift valleys.

Explanation:

Plate tectonics theory states that Earth's lithosphere (outer rigid layer) is broken into tectonic plates that move slowly and constantly over the asthenosphere. Let's analyze each option:

1. "Plates sometimes move closer to one another" only describes one type of plate interaction (convergence) but does not capture the core of the theory.
2. "Sections of Earth that shift are part of Earth’s asthenosphere" is incorrect; the shifting plates are part of the lithosphere, not the asthenosphere.
3. "Sections of Earth’s continents are in slow, constant movement" aligns with the core idea: tectonic plates (which carry continental crust) move slowly and continuously.
4. "Parts of the ocean floor move as they are carried by rift valleys" is incorrect; rift valleys form from plate movement, not the other way around, and this only addresses oceanic plates, not the full theory.

Answer:

Sections of Earth's continents are in slow, constant movement.