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.
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Question: Category: SPORTS 
Clue: Football's imaginary plane which neither team may cross until the ball is snapped

Answer: the line of scrimmage


Question: Category: RELIGION 
Clue: Some 3 million pilgrims visit this small French town annually

Answer: lourdes


Question: Category: STAMPS 
Clue: In 2004 the Post Office honored the "Greatest Generation" with a stamp of this national memorial in D.C.

Answer:
the world war ii memorial