BidBuy Is the World's Leading Online Auction Company

BidBuy is the world's leading online auction company. When BidBuy was founded ten years ago it was the first online auction company, and it has been the leader since it was founded. Although there are other firms in the industry, BidBuy controls over 75% of the market in the United States, and three additional firms control another 20% of the U.S. market. One of the aspects of BidBuy that keeps users from changing to other online auction companies is the large user base BidBuy has built and a feedback rating system that allows buyers and sellers to rate their satisfaction with each other following each transaction. This allows users to build a reputation for honesty and trustworthiness. Sellers with a high feedback rating tend to receive more bids on their auctions and a higher price for their goods. To help facilitate payment transfers between buyers and sellers following successful online auctions, companies such as DollarDog have been founded, and these companies have facilitated growth for BidBuy. Having attained a 75% market share in the U.S., BidBuy has begun expanding internationally, opening its own sites in some countries and purchasing incumbents in others. In its international expansion, BidBuy has allowed its individual companies to customize their offerings according to the needs and desires of the countries in which they operate and when these companies are successful, BidBuy works to transfer these successful capabilities throughout the firm.
-Factors such as BidBuy's feedback rating system that are valuable to the company's customers but which are not useful on other online auction sites are examples of

A) first-mover advantages.
B) complementors.
C) substitutes.
D) customer-switching costs.