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

Answer: liver


Question: Category: HISTORY 
Clue: In June 1987 she became the first British prime minister in the 20th c. elected to 3 straight terms

Answer: margaret thatcher


Question: Category: GREECE 
Clue: The mainland of Greece forms the southern part of this peninsula

Answer:
the balkan peninsula