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: "HARD" QUESTIONS 
Clue: Stubborn

SOLUTION: hard-headed

PROBLEM: Category: POWER TO THE PEOPLE 
Clue: Citizen's Eco-Drive Thermo is one of these powered by the heat of your body

SOLUTION: wristwatch

PROBLEM: Category: ARCHAEOLOGY 
Clue: Fossils of this primitive "man" have been found in France & Gibraltar as well as the Neander Valley

SOLUTION:
the neanderthal man