Whether a large population is good or not has long been a subject of discussion among economists. It has been argued that the supply of good land is limited. To feed a large population, even poorer land must be made use of and the good land is worked too much. Thus, each person produces less and this means a lower average income that could only be dealt with by a smaller population. Other economists have argued that a large population gives more good ideas for plans and the development of ports, roads and railways, which are not likely to be built unless there are more people who want to use them.One of the difficulties in carrying out a world-wide birth control program lies in the fact that official attitudes to population growth change from country to country. In the developing country where a greatly growing population is pressing hard upon the limits of food and space, the government will try to limit birthrate. In a highly industrialized society, a decreasing birthrate may lead to unemployment be- cause it results in a declining market. So the govermnent of a developed country may well prefer to see a slowly increasing population, rather than one that is in decline. According to the passage, a large population will provide a chance for developing （）.

A. agriculture
B. transport
C. industry
D. national economy