题目内容：
根据以下短文，回答题。Old And Active
It is wellknown that life expectancy is longer in Japan than in most other countries. A recent51also shows that Japan has the longest health expectancy in the world. A healthy long life is the result of the52in social environment. Scientists are trying to53out exactly what keeps elderly Japanese people so healthy, and whether there is a54to be learnt from their lifestyles for the rest of us. Should we make any55to our eating habits, for instance, or go jogging each day before breakfast? Is there some secret56in the Japanese diet that is particularly beneficial57the human body? Another factor contributing to the rapid population aging in Japan is a58in birthrate. Although longer life should be59, it is actually considered a social problem. The number of older people had doubled in the last half century and that has60pension and medical costs. The country could soon be61an economic problem, if there are so many old people to be looked after, and relatively few younger people working and paying62to support them. Raising the retirement age from 65 to 70 could be one63to the problem. Work can give the elderly a64of responsibility and mission in life. It’s important that the elderly play active65in the society and live in harmony with all generations.
A．book B．report C．paper D．news
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