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: RIVERS 
Clue: The mouth of this 2315-mile-long river lies in the Mississippi River 17 miles above St. Louis
the missouri

Category: MILITARY TRAINING BASES 
Clue: Service branch with a San Diego recruit depot & a Yuma air station
marines

Category: PAINTERS 
Clue: The title of his 1885 work "Halibut Fishing" was changed to the more familiar title "Fog Warning" years later

winslow homer