The correct answer is option 2: "Dwarf planets of our solar system."

Ceres, Haumea, Makemake, and Eris are the names of four dwarf planets that are a part of our solar system. Dwarf planets are celestial bodies that are similar to planets in terms of their shape and size but have not cleared their orbits of other debris. They are different from regular planets because they do not meet all the criteria defined by the International Astronomical Union (IAU) for a planet.

Ceres is the largest object in the asteroid belt located between Mars and Jupiter and was classified as a dwarf planet in 2006. Haumea is a dwarf planet located beyond Neptune in the Kuiper belt and was discovered in 2004. Makemake is another dwarf planet in the Kuiper belt, discovered in 2005. Eris is the most massive and distant known dwarf planet in our solar system, located in the scattered disc region and was discovered in 2005.

These four celestial bodies are often studied alongside other planets and objects in our solar system to understand its composition and evolution. They provide valuable insights into the dynamics and history of our cosmic neighborhood.