By examining customer checkout details, supermarkets have learned that people who are buying beer typically also buy a bag of salty snacks. As a result of this finding, supermarkets often place displays of beer near the chips and pretzel aisle. Which of the following methods of processing information is most likely to have been used for discovering such information?
a. Authenticating
b. Perceptual filtering
c. Bar coding
d. Data mining
e. Optical scanning