The dwarf planet that lies in the main asteroid belt is:

Ceres is the largest object in the main asteroid belt and the only dwarf planet found in the inner solar system.

Discovery:

• Ceres was discovered on 1 January 1801 by the Italian astronomer Giuseppe Piazzi at Palermo, Sicily.
• It was the first asteroid ever discovered.
• It is named after Ceres, the Roman goddess of agriculture and grain; the word "cereal" comes from the same name.

Changing status:

• When it was discovered, Ceres was first considered a planet.
• Later, as many similar bodies were found, it was classified as an asteroid.
• In 2006, the International Astronomical Union classified it as a dwarf planet, because it is round but has not cleared its orbit.

Physical features:

• Ceres is about 940 km in diameter.
• It contains about one-third of the total mass of the asteroid belt.
• It is round because its gravity is strong enough to pull it into a near-spherical shape.
• It has a rocky core and a mantle rich in water ice, and may have had, or still has, a layer of salty liquid water beneath its surface.

Bright spots and Dawn mission:

• NASA's Dawn spacecraft orbited Ceres from 2015 to 2018, after visiting the large asteroid Vesta.
• Dawn was the first spacecraft to orbit two different bodies beyond the Earth-Moon system.
• It found bright spots in Occator Crater, made of salt deposits (sodium carbonate) left behind by briny water.
• It also found Ahuna Mons, a cryovolcano (ice volcano).

Other recognised dwarf planets:

• The IAU officially recognises five dwarf planets: Ceres, Pluto, Haumea, Makemake and Eris.
• All except Ceres lie in the outer solar system, beyond the planets.

Why not the other options?

• ✗Eris, Makemake and Haumea are dwarf planets found in the distant outer solar system, not in the asteroid belt.