Question

which was originally classified as a planet and then reclassified to a dwarf planet?
ceres
eris
pluto
jupiter

Explanation:

Pluto was discovered in 1930 and classified as the ninth planet from the Sun. However, in 2006, the International Astronomical Union (IAU) redefined the definition of a planet. According to the new definition, a planet must clear its orbit of other debris. Pluto, due to its size and the fact that it shares its orbit with other objects in the Kuiper Belt, did not meet this criterion. As a result, it was reclassified as a dwarf planet. Ceres was initially classified as a planet when discovered in 1801 but was later reclassified as an asteroid. In 2006, it was reclassified as a dwarf planet. Eris is a dwarf planet that was discovered in 2005 and was never classified as a full - fledged planet. Jupiter is a gas giant and has always been classified as a planet.

Answer:

Pluto