I believe the answer is free indirect discourse, but it is an epistolary novel as well
John was as stubborn as a mule.
Answer:
"Students."
Explanation:
"Students" is a noun, since it is a person, place or thing, along with being plural, as represented by the 's' on the end. Some others are nouns, but not plural. Hope this helps!
Depending on the additional context (if any is given), the answer is likely "gold and ivory."