Question

when the mantle material is heated by the core, it rises towards the surface. as it rises, it cools, moves horizontally, and then becomes cooler and denser. finally, it sinks. this creates a

cell.

Explanation:

The described process involves the movement of mantle material due to heating (rising) and cooling (sinking), which is characteristic of a convection cell. In geology (a subfield of Natural Science, specifically Earth Science which can be under Geography or its own subfield, but here the process is about heat - driven fluid - like movement of mantle, related to convection), convection cells form when a fluid is heated, becomes less dense and rises, then cools, becomes denser and sinks, creating a circular flow. So the word to fill in is "convection".

Answer:

convection