问题详情

The author refers to the impact of railroads before the late 1860’s as "limited" because ______.

A．the track did not take the direct route from one city to the next

B．passengers and freight had to transfer to other modes of transportation to reach western destinations

C．passengers preferred stagecoaches

D．railroad travel was quite expensive

请帮忙给出正确答案和分析，谢谢！