 What is the simplest description of what Miss Meuhl and Retief are in the minds of the Groacian race? Why is this significant to the story?
I've been tied up every off-duty hour since I got here—" "You can't offend the Groaci," Miss Meuhl said sharply. "You've been here on Groac for four years, Miss Meuhl. Retief backed, rounded a corner into a narrow alley-like passage, deserted, silent ... except for the following Groacian. Two Groaci wearing heavy eye-shields and elaborate crest ornaments indicative of rank rose as Retief entered the room. "All our efforts," Miss Meuhl said, "to live down that terrible episode! I understand that a Terrestrial task force stood off Groac and sent a delegation down to ask questions. After being securely caged, they were exhibited to the gentle Groaci public. "It is true, they were Terrestrials.
 They are aliens. This is significant because Groacians see humans as alien to their planet, which helps the reader understand how prejudice develops on Groac.
 They are illegal space travelers. This is significant because the crimes of explorers like them are what prompted the Groaci to hide the first human cruiser that arrived.  They are colonialists. This is significant because it is Miss Meuhl and Retief’s desire to colonize Groac that fuels the Groacian hatred of foreigners.  They are slaves. This is significant because it helps the reader understand that Retief is lashing out as a result of being oppressed for so long.  They are aliens. This is significant because Groacians see humans as alien to their planet, which helps the reader understand how prejudice develops on Groac.