Detailed Instructions: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Among the entities, try to find the best entity that is most likely to fill in "_" and classify the answers based on options.
Q: It is just over one month until the New Horizons spacecraft arrives at Pluto on 14 July - the first ever visit to the dwarf planet and one of the most anticipated space missions this millennium. And its impending arrival has caused the Plutonian system to be cast under more scrutiny than it ever has been before. Now, in the latest research, astronomers have taken the most detailed look at its moons - and found some surprising results, namely that they have chaotic rotations and strange surface compositions. The study, carried out by the University of Maryland, examined how Pluto and its large satellite Charon interact with the four smaller moons - Kerberos, Styx, Nix and Hydra.University of Maryland study revealed characteristics of Pluto's moonsMost of the moons were found to have chaotic, tumbling rotationsBut, surprisingly, they seem to be in stable orbits around Pluto and CharonAnd four of the five moons appear to be as bright as white sand 
 Questions:The moon _ is almost half the size of Pluto, and it is so big that Pluto and Charon are sometimes referred to as a double dwarf planet system. (A) New Horizons (B) Pluto (C) Plutonian (D) University of Maryland (E) Charon (F) Kerberos (G) Styx (H) Nix (I) Hydra
A:
(E)