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: SUCH GOOD CHEMISTRY 
Clue: A U.S. nuclear weapon using this element, Co, has been termed a doomsday device, as it would wipe out life on Earth

SOLUTION: cobalt

PROBLEM: Category: TRAVEL INDIANAPOLIS 
Clue: Union Station has a hotel that features these sleeping cars converted into hotel suites

SOLUTION: pullman cars

PROBLEM: Category: INVENTORS & INVENTIONS 
Clue: After steamboat success, he was urged to work on submarine-launched torpedoes by Pres. Jefferson

SOLUTION:
robert fulton