TASK DEFINITION: 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.
PROBLEM: Category: LANGUAGES 
Clue: The 2 languages on the Rosetta Stone

SOLUTION: egyptian & greek

PROBLEM: Category: IT'S A DOG'S LIFE 
Clue: Familiar to fans as "Marmaduke", this lovable breed was a favorite of Elvis, who had 2 at Graceland

SOLUTION: a great dane

PROBLEM: Category: SUN 
Clue: In the main reaction making the sun's energy, 2 of these nuclear particles fuse & one becomes a neutron

SOLUTION:
protons