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: THE BIG BANGLADESH 
Clue: The green on the flag of Bangladesh represents its lush vegetation; the red circle in the middle is this
the sun

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

Category: THE HUMAN BODY 
Clue: This tube of cartilage branches into 2 major bronchi that enter the lungs

the trachea