[单项选择]In recent years, railroads have been combining with each other, merging into supersystems, causing heightened concerns about monopoly. As recently as 1995, the top four railroads accounted for under 70 percent of the total ton-miles moved by rails. Next year, after a series of mergers is completed, just four railroads will control well over 90 percent of all the freight moved by major rail carriers. Supporters of the new supersystems argue that these mergers will allow for substantial cost reductions and better coordinated service. Any threat of monopoly, they argue, is removed by fierce competition from trucks. But many shippers complain that for heavy bulk commodities traveling long distances, such as coal, chemicals, and grain, trucking is too costly and the railroads therefore have them by the throat. The vast consolidation within the rail industry means that most shippers are served by only one rail company. Railroads typically charge such" captive" shippers 20 to 30 perce
A. shippers will be charged less without a rival railroad.
B. there will soon be only one railroad company nationwide.
C. overcharged shippers are unlikely to appeal for rate relief.
D. a government board ensures fair play in railway business.