Which of the following bodies is considered a small celestial object that produces meteors upon entering Earth's atmosphere?

A meteoroid is indeed considered a small celestial object that produces meteors when it enters Earth's atmosphere. Meteoroids are typically defined as debris in space that is smaller than an asteroid and can vary in size from a grain of dust to up to a meter wide. When a meteoroid travels through the Earth’s atmosphere at high speed, the friction between the meteoroid and the atmospheric particles causes it to heat up and emit light, resulting in what we commonly refer to as a meteor or "shooting star."

In contrast, a meteorite is a fragment of a meteoroid that survives its passage through the atmosphere and lands on Earth. An asteroid is a larger rocky body that orbits the Sun, and while comets consist of ice and dust and have a more elaborate structure, they do not typically produce meteors in the same way that meteoroids do. The specific action of creating a visible meteor as it burns up upon atmospheric entry is unique to meteoroids.