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.

[EX Q]: Category: FOREIGN NATIONAL PARKS 
Clue: Great Gobi Desert
[EX A]: mongolia

[EX Q]: Category: YOU NEED THERAPY 
Clue: In the hyperbaric type of this "therapy", the patient inhales the pure gas in a large chamber
[EX A]: oxygen

[EX Q]: Category: TRANSPORTATION SLANG 
Clue: Rhyme time term for a huge 18-wheeler
[EX A]:
big rig