TASK 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.
PROBLEM: Category: THE CHIEFS 
Clue: This Chief Justice in the Dred Scott decision earlier served as Attorney General under Andrew Jackson

SOLUTION: taney

PROBLEM: Category: PEN NAMES 
Clue: He came out of "The Jungle" to write juvenile novels as Clarke Fitch

SOLUTION: upton sinclair

PROBLEM: Category: PEOPLE & PLACES 
Clue: This other term for a person from Bulgaria is just 2 letters shorter than the country itself

SOLUTION:
bulgar