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: 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: ANCIENT HISTORY 
Clue: Circled 7 times by the Israelites in Joshua, it's said to be the world's oldest walled city
[EX A]: jericho

[EX Q]: Category: 1989 NO. 1 HITS 
Clue: The Billboard Book of No. 1 Hits says this song brought mail from history teachers who hailed it as an educational aid
[EX A]:
\"we didn\'t start the fire\"