Final answer:
Convection is closely associated with plate tectonics, as it drives the movement of tectonic plates, which can result in geological phenomena like mountain building and volcanic eruptions.
Step-by-step explanation:
The phenomenon of hot gas rising and cool gas falling due to convection is most closely associated with plate tectonics. This is because the Earth's mantle undergoes convection, a process where hotter, less dense material rises and cooler, denser material sinks. This convection within the mantle is one of the main drivers of the movement of tectonic plates. These plates can collide, move apart, or slide against each other, leading to various geological features and phenomena such as mountain building, earthquakes, and volcanic eruptions. Sedimentary rocks, while they may be formed through processes related to plate tectonics, such as erosion and sediment deposition, are not directly created by mantle convection.