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: PAC-MAN 
Clue: Rep. Delahunt said a 2005 bill making it harder to qualify for this "was written for and by the credit card industry"
bankruptcy

Category: TRANSPORTATION 
Clue: In the 19th century Gustavus Swift developed this type of railway car to preserve his packed meat
refrigerator car

Category: DEAD SCIENTISTS' SOCIETY 
Clue: This Russian famously conditioned dogs to salivate every time a bell rang

pavlov