Explanation:

Third option is correct.

The International Astronomical Union (IAU), officially named the 2 smallest moons orbiting Pluto. These are Kerberos & Styx.

In order of distance from Pluto, they are Charon, Styx, Nix, Kerberos, and Hydra. Charon, the largest of the five moons, is mutually tidally locked with Pluto, and is massive enough that Pluto–Charon is sometimes considered a double dwarf planet.