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: CAN'T SMILE WITHOUT YOU 
Clue: It's the hard outer layer of a tooth
enamel

Category: "D"-VIDE 
Clue: In the book of Revelation, he rides the pale horse
death

Category: GENERAL SCIENCE 
Clue: This outer planet discovered by Herschel has a 98-degree axial tilt & solstices 42 years apart

uranus