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: WHAT A CARD! 
Clue: Ken Jennings used these briefly displayed items to get ready to play "Jeopardy!"
flashcards

Category: ANCIENT GREEKS 
Clue: This actor of the 6th century B.C. is credited with introducing the use of masks on stage
thespis

Category: MYTHOLOGY 
Clue: This god was the trumpeter of the sea, & his trumpet was a large shell

triton