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

SOLUTION: the line of scrimmage

PROBLEM: Category: ZOOLOGY 
Clue: Unlike the octopus or squid, the nautilus may have up to 90 of these armlike appendages

SOLUTION: tentacles

PROBLEM: Category: HOLIDAYS & OBSERVANCES 
Clue: Matthew Maguire, a machinist, & Peter J. McGuire, a union founder, are credited with creating this holiday

SOLUTION:
labor day