Psychologically there are two dangers to be guarded against in old age. One of these is undue absorption in the past. It does not do to live in memories, in regrets for the old days, or in sadness about friends who are dead. One’’s thoughts must be directed to the future, and to things about which there is something to be done. This is not always easy; one’’s own past is a gradually increasing weight. It is easy to think to oneself that one’’s emotions used to be more active than they are, and one’’s mind more keen. If this is true it should be forgotten, and if it is forgotten it will probably not be true. The other thing to be avoided is clinging tightly to youth in the hope of sucking vigor from its vitality. When your children are grown up they want to live their own lives, and if you continue to be as interested in them as you were when they were young, you are likely to become a burden to them. I do not mean that one should be without interest in them, but one’’s interest should be thoughtful and, if possible, kindly but not unduly emotional. Animals become indifferent to their young as soon as their young can look after themselves, but human beings, owing to the length of early childhood, find this difficult. I think that a successful old age is easiest for those who have strong impersonal interest involving appropriate activities. It is in this sphere mat long experience is really fruitful, and it is in this sphere that the wisdom born of experience can be exercised without being oppressive. It is no use telling grown-up children not to make mistakes, both because they will not believe you, and because mistakes are an essential part of education. But if you are one of those who are incapable of impersonal interest, you may find that your life will be empty unless you concern yourself with your children and grandchildren. In that case you must realize that while you can still render them material services, such as making them an allowance or knitting them sweaters, you must not expect that they will enjoy your company. The first paragraph of the passage suggests________.

A. modern society has made old people more fragile
B. there is still much one can do in his old age
C. in old age one should forget his past
D. in old age one should switch his thoughts to the future