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 consistency, answers should be in all lower cased letters.
--------
Question: Category: "N" JOY 
Clue: A songbird, or the last name of nursing pioneer Florence

Answer: nightingale


Question: Category: "Y"? 
Clue: You can split the atom or even do barrel rolls using this toy

Answer: a yo-yo


Question: Category: CORPORATE AMERICA 
Clue: Named for the Mississippi area it served, this airline began in 1924 as a crop-dusting service

Answer:
delta airlines