Which statement describes plate tectonic theory?

• A. The oceans rise and fall with tides
• B. The lithosphere is divided into tectonic plates
• C. The atmosphere is divided into layers
• D. The Earth is flat

Answer: (B)

Plate tectonic theory describes the Earth's outer shell as made of rigid pieces called tectonic plates that slowly move over the underlying mantle. The statement that the lithosphere is divided into tectonic plates captures this idea exactly, because it identifies the lithosphere as segmented into movable plates. These plates—consisting of crust plus the uppermost mantle—ride on the weaker asthenosphere, driven by convection currents in the mantle. Interactions at plate boundaries explain most earthquakes, volcanoes, and mountain-building processes. The other statements don’t describe plate tectonics: tides are caused by gravity acting on the oceans; the atmosphere being layered concerns atmospheric science; and the Earth is flat is incorrect.