Which of the following best illustrates the transaction fee revenue model?
A.
eBay receives a small fee from a seller if a seller is successful in selling an item.
B.
Epinions receives a fee after steering a customer to a participating Web site where he or she makes a purchase.
C.
Flickr provides basic services for free, but charges a premium for advanced services.
D.
Apple accepts micropayments for single music track downloads.