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.

Category: LEISURE ACTIVITIES 
Clue: In origami, folding paper down, away from you, is a mountain fold; folding it up toward you is this opposite
a valley

Category: SUN 
Clue: In the main reaction making the sun's energy, 2 of these nuclear particles fuse & one becomes a neutron
protons

Category: SPANS 
Clue: The Confederation Bridge, opened in 1997, is the first highway link to this Canadian island province

prince edward island