Answer:
Pluto is a dwarf planet.

Explanation:
Pluto is considered a dwarf planet because it does not meet all the criteria to be classified as a full-fledged planet. The International Astronomical Union (IAU) defines a planet as a celestial body that orbits the Sun, is spherical in shape, and has cleared its orbit of other debris. While Pluto orbits the Sun and is spherical in shape, it has not cleared its orbit of other debris, which is why it is classified as a dwarf planet.

Criteria for a Planet:
To be classified as a planet, a celestial body must meet the following criteria:

1. Orbits the Sun: A planet must orbit the Sun directly and not be a satellite of another planet.

2. Spherical Shape: A planet must have sufficient mass to pull itself into a nearly round shape. This is due to the force of gravity acting evenly from all directions.

3. Cleared its Orbit: A planet must have cleared its orbit of other debris, meaning it has become the dominant gravitational force in its orbit by either consuming or ejecting other objects.

Why is Pluto a Dwarf Planet?
Pluto was originally classified as the ninth planet in our solar system when it was discovered in 1930. However, in 2006, the IAU redefined the definition of a planet and established the criteria mentioned above. Pluto does not meet the third criterion of clearing its orbit, as it shares its orbit with other objects in the Kuiper Belt, a region of the solar system beyond Neptune.

As a result, Pluto was reclassified as a dwarf planet. A dwarf planet is a celestial body that orbits the Sun, is spherical in shape, but has not cleared its orbit of other debris. Other examples of dwarf planets include Eris, Haumea, Makemake, and Ceres.

In conclusion, Pluto is a dwarf planet because it does not meet the criteria set by the IAU to be classified as a full-fledged planet. It orbits the Sun, is spherical in shape, but has not cleared its orbit of other debris.