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: THE TOWER 
Clue: Lightning not only strikes the same place twice, it strikes this 110-story Chicago tower hundreds of times a year
sears tower

Category: "TWO" 
Clue: It features Jefferson on the front & the signers of the Declaration on the back
two-dollar bill

Category: ASTRONOMY 
Clue: In 1979 these were discovered around Jupiter; Saturn has them too

rings