Picture the journey of a small rock in three stages, like three different names for the same object at different points in its trip.
- Stage one, out in space, far from any planet, it is called a meteoroid.
- Stage two, it rushes into Earth's atmosphere at speeds that can reach tens of kilometres per second. Air resistance heats its surface so much that it glows brightly, and we see a fast streak of light, this glowing streak is the meteor.
- Stage three, most meteoroids burn up completely before reaching the ground. If a chunk does survive and lands, we then call that surviving chunk a meteorite.
The question is asking about the object while it is entering the atmosphere, which is exactly stage two, so the answer is meteor, not planet, sun or moon, since those three describe completely different kinds of large celestial bodies.