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: INVENTIONS 
Clue: 11-year-old Frank Epperson invented this by accident when his fruit drink froze after being left outside overnight
the popsicle

Category: ON EXHIBIT 
Clue: The Chinese government, which controls all of these in the U.S., won't let a new one be named until it's 100 days old
giant pandas

Category: MATERIALS 
Clue: The name of the sheet seen here is derived from the name of this material

celluloid