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.

[EX Q]: Category: THE ARMED SERVICES 
Clue: In September 1997 this branch of the U.S. Armed Services celebrated its 50th anniversary
[EX A]: u.s. air force

[EX Q]: Category: WORLD EVENTS 
Clue: In 2003, 120 years after it made headlines, a book on this was subtitled "The Day the World Exploded"
[EX A]: the eruption of krakatoa

[EX Q]: Category: LANDMARKS 
Clue: Some of its pieces, which weighed up to 50 tons, were quarried at Marlborough Downs, about 20 miles away
[EX A]:
stonehenge

