Allowing third-party sellers to list their products on Amazon is controversial. Why would Amazon allow products sold by others to appear on its site?
a. Selection attracts consumers.
b. A network effect competitive advantage is created where more buyers attract more sellers, giving Amazon an advantage over any rival attempting to create a similar marketplace.
c. Although products are sold by third parties, Amazon gains valuable data on things such as customer browsing habits and sales.
d. Amazon's brand is reinforced as a first-choice shopping destination.
e. All of the above.