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.

[Q]: Category: BLACK IS BACK 
Clue: The "Black Spot" is a dreaded summons handed out by pirates in this 1883 Robert Louis Stevenson tale
[A]: treasure island


[Q]: Category: GEOGRAPHY 
Clue: This Sudanese capital is located at the junction of the Blue & the White Nile
[A]: khartoum


[Q]: Category: NUMBER, PLEASE 
Clue: We just got a call from the authorities to evacuate, in the system known as "reverse" this
[A]:
9-1-1