Which of these best explains why earth’s tectonic plates move? convection currents in the asthenosphere make fluid particles move. cooling causes contraction and shifting of the fluid particles in the lithosphere. cooling causes expansion and shifting of the fluid particles in the asthenosphere. convection currents in the lithosphere make fluids move in a circular motion.

Convection currents in the lithosphere make fluids move in a circular motion.

Explanation:

As we know, the earth's crust is positioned just above another layer of our planet: the mantle. It is composed basically of magma, which is nothing more than rocks in the liquid state, with a slightly dense consistency, all because of the high temperatures inside the Earth. The tectonic plates literally float on the magma.

In this way, what makes the tectonic plates move is precisely the movement of this magma! And this movement does not happen in any way, but rather follows a cyclic variation, which we call chains or convection cells of the Earth.

Convection cells move in this way because temperatures are higher in the areas closest to the nucleus. The magma located farther in the bottom heats up and, therefore, becomes lighter and rises. When it reaches the highest areas, it loses temperature, becomes denser and descends again towards the nucleus, where this process is continued.

Therefore, the movement of the magma in the form of convection currents causes the Earth's mantle to function as if it were a "moving conveyor" on which the tectonic plates of the Earth's crust move. Thus, the direction of the various existing convection cells also determines the direction of the different plates influenced by them.

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.