Which theory of plate movement involves magma rising all the way from the lower mantle to spread apart plates A. Slab-push?

The theory that involves magma rising from the lower mantle to spread apart tectonic plates is known as "mantle convection," not slab-push. In mantle convection, heat from the Earth's core causes molten rock in the mantle to rise, creating convection currents that can lead to the movement of tectonic plates at the surface. Slab-push, on the other hand, refers to the process where the weight of a subducting plate pushes the rest of the plate away from the mid-ocean ridge.