The part of the Earth's interior that is inferred to have convection currents that cause tectonic plates to move is the mantle.

Here's why:

* Convection: The mantle is a thick layer of hot, semi-solid rock. Heat from the Earth's core causes the mantle to heat up and become less dense. This less dense material rises. Cooler, denser material sinks back down, creating a circular flow called convection currents.

* Tectonic Plate Movement: These convection currents in the mantle act like giant conveyor belts, dragging the tectonic plates on the Earth's surface along with them. The movement of these plates is responsible for phenomena like earthquakes, volcanoes, and mountain formation.

Let me know if you'd like more details about how convection currents work or the different types of tectonic plate boundaries!