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 consistency, answers should be in all lower cased letters.

Category: ECONOMICS 
Clue: After deducting all expenses from your gross profit, you're left with this
net

Category: ANCIENT TIMES 
Clue: Julius Caesar said this region was divided into 3 parts; Augustus divided it into 4, including Aquitania
gaul

Category: FIX THE PROVERB 
Clue: The whales have oars

the walls have ears