Dudley Jenkins runs a services swapping web site where people can trade services online. For instance, a user on the web site can offer babysitting services to another user in return for getting his house painted. Dudley had expected this to be a successful venture because swapping web sites seemed to work well for collectibles like stamps and antiques. Given the high levels of unemployment in the economy, he was convinced of the web site's success because it would allow people to exchange one service for another without the use of money. However, Dudley was unable to sustain the business for even a year. Which of the following, if true, is most likely to explain this outcome? A. Taxes in the country were increased leading to a fall in purchasing power. B. The web site did not attract a user base that was large enough to ensure that customer requirements matched. C. The volume of online retail trade in the country has registered an impressive increase in recent times. D. The level of unemployment was at an all-time high when the web site was operational. E. There have been serious concerns in the past year about the security of credit card information collected by web sites that enable online transactions.