Question

add a comma, semicolon, or colon if needed. otherwise, submit the text without any additional punctuation. as of 2014, the dwarf planet pluto has five known moons charon, nix, hydra, kerberos, and styx.

Explanation:

The sentence already has a comma after "2014" and commas separating the moon names. No additional comma, semicolon, or colon is needed before "Charon" as it is part of the list of Pluto's moons.

Answer:

As of 2014, the dwarf planet Pluto has five known moons: Charon, Nix, Hydra, Kerberos, and Styx.