题目内容：
根据短文内容，回答题。Man cannot go on increasing his number at the present rate. In the next 30 years man will face a period of crisis. Some experts believe that there will be a widespread food ____51____ . Other experts think this is too pessimistic (悲观的), and that man can prevent things from ____52 ____worse than they are. now. But remember that two thirds of the people in the world are under-nourished or starving now.
One thing that man can do is to limit the ____53 ____of babies born. The need for this is obvious, but it is not easy to achieve. People have to be ____54____ to limit "their families. In the countries of the population ____55 ____, many people like big families. The parents think that this makes a bigger income for the family and ensures there will be someone in the family who will look ____56____ them in old age.
Several governments have ____57____ birth control policies in recent years. Among them are Ja-pan, China, India and Egypt. In some cases the results have not been successful. Japan has been an ____58____ . The Japanese adopted a birth control policy in 1948. People were ____59____ to limit their families. The birth rate fell from 34.3 per thousand per year to about 17.0 per year ____60____ present.
_________ A．need
B．want
C．absence
D．shortage
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