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: "E" BAY 
Clue: Thinking green, biologist Ernst Haeckel coined this term for the way animals interact with the environment
ecology

Category: PLAYBILL 
Clue: This musical's "American Dream" ended on B'way after 4,097 performances--& a lot of helicopter flights
miss saigon

Category: TRY "TRI" AGAIN 
Clue: The period that lasted from about 245 million to 208 million years ago

triassic