阅读材料 回答题。Man cannot go on increasing his number at

阅读材料，回答题。
Man cannot go on increasing his number at the present rate. In the next 30 years man will faca period of crisis. Some experts believe that there will be a widespread food___ 51 ____. Other experthink this is too pessimistic (悲观的), and that man can prevent things from___ 52 ____worse tha they are now. But remember that two thirds of the people in the world are under-nourished or stmving 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 Japan, 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 1921~3. 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.
________ 查看材料
A.Need
B.want
C.Absence
D.shortage
请帮忙给出正确答案和分析，谢谢！