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.

Q: Category: MARK ANTONYMS 
Clue: The traditional mark of someone who can't sign his name has this opposite in tic-tac-toe

A: o
****
Q: Category: ON THE COAST 
Clue: A 19th c. "Committee of Vigilance" fought the crime that gave part of San Francisco this North Africa-inspired nickname

A: the barbary coast
****
Q: Category: STATE THE NATIONAL PARK 
Clue: Carlsbad Caverns National Park

A:
new mexico
****