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.

Explanation:

According to the 2006 International Astronomical Union (IAU) definition of a planet, one of the criteria is that a planet must clear the neighborhood of its orbit. Pluto fails this criterion, so to remain a planet it would need to meet this requirement.

Answer:

Pluto would need to clear the neighborhood of its orbit.