单选题
Technological development has historically been a powerful driver of globalization, especially over the past two centuries. In agriculture, in particular, technical change underpinned the industrial revolution, improvements in nutrition, and a surge in world population. Interactions between population increases and technical changes in agriculture and industry, mostly since the nineteenth century, converged to expand trade and flows of finance and labor. These have been the essence of globalization. The integration of the world economy would have been impossible without the technological developments in agriculture that proved wrong predictions of the inevitability of world famine. Technology further supported significant improvements in world food production and food security. Although substantial numbers of people are still food insecure, this is due not to lack of overall production but is related to the location of production, income levels, and access to food by countries, households, and individuals living on the edge of subsistence. Since the 1960s, growth in world food supplies outpaced even the unprecedented increases in food demand caused by jumps in incomes and the doubling and redoubling of population. Moreover, additional production came from virtually the same cropland base. 1.4 billion hectares of land was planted to crops in 1961 compared with the 1.5 billion hectares that in 1998 yielded twice the amount of grain and oilseeds. Food prices too have declined to their lowest levels in history. Consumers are able to eat better while spending less and less of their budgets on food, diversifying demand for other goods and services. Changes in demand have spurred countries' specialization in production, fueling world trade and investment flows. The currently favorable dynamic balance between overall food supply and demand was not inevitable, however. Nor should it be taken for granted that the balance will persist without public intervention. Progress in the past century resulted from successful interaction between farmers, input suppliers, and a publicly supported research and extension system that furnished innovations and knowledge to the world for free. Little land now remains on which to expand agricultural production, so crop and livestock yields must continue to increase for the next several decades. Production must be sustained, at these much higher levels, for the foreseeable future in the face of environmental, biological, and other factors that may undermine past gains. Thus, continued strong performance in research and innovation is essential to maintain favorable food balances over the next half century.
单选题
What have been the driving forces of globalization according to the author?