单项选择题

It remains to be seen whether the reserves of raw materials would be sufficient to supply a world economy which would have grown by 500 per cent. South-East Asia alone would have an energy consumption five times greater than that of Western Europe in 1970. Incidentally, if the underdeveloped countries started using up petrol at the same rate as the industrialized areas, then world reserves would already be exhausted by 1985.
 All this only goes to show just how important it is to set up a plan to conserve and divide up fairly natural resources on a worldwide scale.
 This is a matter of life and death because world population is exploding at an incredible rate. By the middle of the next century population will expand every year by as much as it did in the first 1500 years after Christ. In the southern, poor, parts of the globe, the figures are enough to make your hair stand on end. Even supposing that steps are taken to stabilize world population in the next fifty years, the number of inhabitants per square kilometer will increase by from 4 in the United States to 140 in South-East Asia. What can we do about it
 In the first hypothesis we do nothing. By the year 2008, the southern parts of the world would then have a population greater than the total population today. Calcutta would have 65 million inhabitants. It is unthinkable.
 Alternatively, we could start acting right now to bring births under control within fifteen years so that population levels off. Even then the population in the southern areas would not stop growing for seventy-five years.

If we take immediate action, the population in the southern parts （）

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