What mechanism is responsible for moving tectonic plates?

• A. Gravity forces in the core
• B. Convection currents in the mantle
• C. Surface ocean currents
• D. Solar radiation pressure

Answer: (B)

Mantle convection currents drive plate tectonics. Heat from Earth's interior makes the mantle behave like a very viscous fluid, with hot material rising, cooling, and sinking in large convection cells. The rigid lithospheric plates ride on top of this flowing mantle, so as the mantle moves, it drags the plates along, causing them to move, split, collide, or slide past each other.

Other ideas don’t explain plate motion: gravity acting in the core mainly influences the geodynamo, not plate movement; surface ocean currents are driven by winds and density, not the deep mantle; and solar radiation pressure on such large, slow-moving solid features is negligible.