单项选择题

Rupert Murdoch once described them as the "rivers of gold"—the lucrative classified advertising revenues that flowed into big newspaper groups, But the golden rivers are being diverted online as the Internet breaks the grip that local and regional newspapers once held over their advertising markets.
Typically, a local newspaper would expect to get some 80% of its revenue from advertising, of which around two-thirds would come from classifieds. But last year in the San Francisco Bay area, job ads worth some $ 60 million were lost from newspapers to the web, reckons Classified Intelligence, a consultancy. Emap, a British publisher, recently gave warning of a 30% decline in recruitment ads in one of its titles, Nursing Times, following the launch of a free web site for jobs in Britain’s National Health Service.
The Internet has become the fastest-growing advertising medium. Online ad revenues reached $ 5.8 billion in the first six months of this year in America, up 26% on the same period last year, according to a joint study by the Interactive Advertising Bureau and Coopers. In Britain, online ad revenues surged by 62% in the same period to almost ￡500 million ($ 870 million).
Search advertising—the small text-ads that appear alongside Google and Yahoo Searches— account for 40% of the online ad market. Another 20% goes to display ads and 18% to classified advertising. But search advertising can also work like a small ad and will increasingly challenge print classifieds as websites provide localized and more elaborate services for online users.
Perhaps the most significant development came on November 16^th, when Google started up a prototype service called Google Base. It offers a searchable database of free listings, including small ads which can be narrowed down to postal regions. Among its first offerings were used ears. In no time, Google could challenge eBay, whose own auction listings now work much like a giant classified Web site-especially with its "buy-it-now" options. But eBay charges sellers. Even so, it sold more than 450 million items in the three months to September 30th, for almost $11 billion.
In response, most print publishers are expanding online. Mr. Murdoch is buying websites including Property finder and MySpace, a social-networking site. Newspaper groups have teamed up to jointly operate websites to compete with Monster for recruitment ads. But the online operators are expanding too. eBay, for instance, is building a global network of classified sites under the Kijiji brand. It also has a stake in the popular Craigs-list which, having soaked up so many listings around its San Francisco home, is now frightening other newspapers as it expands its free ads service to other cities around the world.
By saying "the golden rivers are being diverted" in Line 3 of Paragraph 1, the author means ______.