Futurists have identified two changes that seem to be central to contemporary social life.

First, the United States is being restructured from an industrial to an information society. Second, modem societies are increasingly shifting from a national to a global economy. Futurists have applied a good many metaphors to these changes, including Daniel Bell's "postindustrial society," Alvin Toffler's "the third wave" and John Naisbitt's "megatrends". Common to these metaphors is the notion that American society is shifting from the production of goods to the production of services and from society based on the coordination of people and machines to a society organized around knowledge. These changes, it is contended, will afford a great variety of choices. The world will increasingly be one of many flavors, not just vanilla or chocolate.

Many observers of contemporary American life believe that we are witnessing a historical change and the first major impact of the shift from an energy economy to an information economy. For 300 years technology has been cast in a mechanical model, one based on the combustion processes that go on inside a star like the sun. The steam engine opened the mechanical age, and it reached its apex with the discovery of nuclear fission and nuclear fusion, which replicated the energy producing processes of a star. We now seem to be moving toward a biological model based on information and involving the intensive use of materials. Although biological processes need physical energy and materials, they tend to substitute information for both. Biological processes "miniaturize" size, energy, and materials by "exploding" information. The human brain is some ten times the size, and weight of the brain of a monkey, but it handles a billion times more information. As a result, high tech industries are information intensive rather than energy or material intensive.

Sociologists have played and will continue to play an important role in assessing and interpreting these developments and other aspects of change.

It can be inferred that underlying the two changes is the change of

A．the instrument of production.

B．the size of the society.

C．the social structure.

D．the economic market.