instruction:
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: PARTICLE PHYSICS 
Clue: To get an element's mass number, add its protons & these
answer:
neutrons


question:
Category: THE HISTORY OF THE WORLD: PART 1 
Clue: This event on October 8-9, 1871 forced thousands of Illinois residents to flee their homes
answer:
chicago fire


question:
Category: HIGH SCHOOLS 
Clue: Led by Lew Alcindor, Power Memorial in NYC won 71 straight games in this sport 1962-65
answer:

basketball