Question

Shelly was surprised to learn the dwarf planet Pluto used to be considered a planet. What would have had to be true for Pluto to remain categorized as a planet?
Pluto would need to have an atmosphere.
Pluto would need to clear the neighborhood of its orbit.
Pluto would need to have a larger moon.
Pluto would need to have water or ice.

Answer 1

The second answer is the correct response, as Pluto is found in the kuiper belt, and there are objects that are roughly the same size as Pluto.

Answer 2

Answer: Pluto would need to clear the neighborhood of its orbit.

Explanation:

Pluto was once a planet and was demoted to dwarf planet in year 2006. A celestial object is considered to be a planet when it is round in shape, it has elliptical orbit around a star and it clears it neighborhood.

Pluto lies in Kuiper belt and there were many more bodies similar to Pluto. Hence, it was demoted to a dwarf planet. Had Pluto been still a planet, it would need to clear neighborhood of its orbit.