Answer: I don't see the choice here, but only 3 dwarf planets are officially recognized as dwarf planets in the Kuiper Belt: Pluto, Haumea, and Makemake. But, there are two more, Ceres and Eris, that are also named, but aren't widely known about.
I believe you could choose 5 (b) for this one.
Best of luck. :)
EDIT: The user took the quiz and the answer was somehow 200.