Part 1. Definition
You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.
Part 2. Example
Category: HOMOPHONIC PAIRS 
Clue: It's a notation on a percussion store to clash
Answer: cymbal symbol
Explanation: "Cymbal" and "symbol" both have the same pronunciations but different meanings, hence they are homophonic pairs. A symbol is the notation and a cymbal is a percussion instrument that clashes and rings.
Part 3. Exercise
Category: THE ARABIAN HORSE 
Clue: The Arabian is a smaller breed than most, having 23 of these, unlike the usual 24 for other horses
Answer:
vertebrae