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.

Category: MR. BODY 
Clue: Fed by the hepatic portal veins, it weighs about a pound more in men than in women
liver

Category: PREHISTORIC TIMES 
Clue: The Stone Age lasted until this metal replaced stone as the primary tool-making material
bronze

Category: PRESIDENTIAL BOOKS 
Clue: In a book by Nixon, the Alger Hiss case & Ike's heart attack were 2 of the "Six" these

crises