(4) All of the above Explanation: Pluto was discovered by clyde Tombaugh in 1930. According to International Astronomical Union (IAU) on August 24, 2006 Pluto is considered as dwarf planet. According to the definition, there are currently eight planets and five dwarf planets known in the solar system. The five dwarf planets are Pluto, Ceres, Eris, Make make and Haumea. Pluto has been given number 134340. Physical Geography (Set: 10)