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.

Category: SLEEP 
Clue: Normally this activity is harmless, but make sure the person doesn't fall down the stairs
sleepwalking

Category: YELLOW THERE! 
Clue: A sushi favorite, hamachi is this type of fish
the yellowtail

Category: NAMESAKES 
Clue: Educated at Rennsselaer Polytechnic, he built railroads & bridges before his amusement park ride

george washington gale ferris