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: RANKS & TITLES 
Clue: Inheriting property & title from her deceased husband made Tz'u-hsi of China this kind of Empress

SOLUTION: dowager

PROBLEM: Category: EUROPEAN CAPITALS 
Clue: This capital lies on the Attica Plain surrounded by mountains including Parnes & Hymettus

SOLUTION: athens

PROBLEM: Category: THE NEAREST CONTINENT 
Clue: Sao Tome & Principe

SOLUTION:
africa