Which statement about dwarf planets is true?

a. pluto was the first dwarf planet to be discovered.

b. all dwarf planets likely contain a mixture of rock and ice.

c. dwarf planets lie beyond the outer planets

"Pluto was the first dwarf planet to be discovered" is the one statement among the following choices given in the question that is true about dwarf planets. The correct option among all the options that are given in the question is the first option or option "a". Pluto was classified as a planet at first but in the year 1930 it was classified as a dwarf planet.