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 consistency, answers should be in all lower cased letters.
PROBLEM: Category: SCIENCE GRAB BAG
Clue: A material called URhGe can be manipulated into being this, lacking electrical resistance

SOLUTION: superconductors

PROBLEM: Category: THE TITANIC
Clue: Gates prevented 700 of these passengers from getting up to the main deck, though they didn't stop Leo in the movie

SOLUTION: third class

PROBLEM: Category: ARCHAEOLOGY
Clue: Carved in 196 B.C., its text was written by priests to honor Ptolemy V

SOLUTION:
the rosetta stone