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: ALL EARS 
Clue: An inner ear disorder kept this first American in space from retuning to space until 1971
alan b. shepard

Category: "TRIPLE" JEOPARDY! 
Clue: Collective term for victories in horse racing's 3 major events
triple crown

Category: ALL ABOUT RIVERS 
Clue: You may be waiting for the Robert E. Lee on a natural one of these raised river banks created by flood waters

levee