The best statement that explains how continents move through plate tectonics is:
D. nuclear radiation in Earth's core; matter heats and moves upwards; then cool areas of the mantle move down.
This option describes the process of mantle convection, which is a key mechanism driving plate tectonics. Hot material from the core heats the mantle, causing it to rise, while cooler, denser material sinks, creating a continuous movement that drives the movement of tectonic plates on the Earth's surface.