No revolutions in technology have as visib

问题：

No revolutions in technology have as visibly marked the human condition as those in transport. Moving goods and people, they have opened continents, transformed living standards, spread diseases, fashions and folk around the world. Yet technologies to transport ideas and information across long distances have arguably achieved even more they have spread knowledge, the basis of economic growth.
The most basic of all these, the written word, was already ancient by 1000. By then China had, in basic form, the printing press, using carved woodblocks. But the key to its future, movable metal type, was four centuries away. The Chinese were hampered by their thousands of ideograms. Even so, they quite soon invented the primitive movable type, made of clay, and by the 13th century they had the movable wooden type. But the real secret was the use of an easily cast metal.
When it came, Europe-aided by simple Western alphabets-leapt forward with it. One reason why Asia’s civilizations, in 1000 far ahead of Europe’s, then fell behind was that they lacked the technology to reproduce and diffuse ideas. On Johannes Gutenberg’s invention in the 1440s were built not just the Reformation and the Enlightenment, but Europe’s agricultural and industrial revolutions too.
Yet information technology on its own would not have got far. Literally: better transport technology too was needed. That was not lacking, but here the big change came much later: it was railways and steamships that first allowed the speedy, widespread dissemination of news and ideas over long distances. And both technologies in turn required people and organizations to develop their use. They got them: for individual communication, the postal service; for wider publics, the publishing industry.
Throughout the 19th century, the postal service formed the bedrock of national and international communications. Crucial to its growth had been the introduction of the stamp, combined with a low price, and payment by the sender. Britain put all three of these ideas into effect in 1840.
By then, the world’s mail was taking off. It changed the world. Merchants in America’s eastern cities used it to gather information, enraging far-off cotton growers and farmers, who found that New Yorkers knew more about crop prices than they did. In the American debate about slavery, it offered abolitionists a low-cost way to spread their views, just as later technologies have cut the cost and widened the scope of political lobbying. The post helped too to integrate the American nation, tying the newly opened west to the settled east.
Everywhere, its development drove and was driven by those of transport. In Britain, travelers rode by mail coach to posting inns. In America, the post subsidized road-building. Indeed, argues Dan Schiller, a professor of communications at the University of California, it was the connection between the post, transport and national integration that ensured that the mail remained a public enterprise even in the United States, its first and only government-ran communications medium, and until at least the 1870s, the biggest organization in the land.
The change has not only been one of speed and distance, though, but of audience. About 200 years ago, a man’s words could reach no further than his voice, not just in range but in whom they reached. But, for some purposes, efficient communication is mass communication, regular, cheap, quick and reliable. When it became possible, it transformed the world.

The word "dissemination" underlined in Paragraph 4 means ______.

A．plantation

B．distribution

C．reception

D．direction