Given the task definition and input, reply with output. 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.

Category: U.S. CITIES 
Clue: Its name includes the county of which it's the seat & the state of which it's the capital

oklahoma city