单项选择题

Someone said to a man, "Travel and see the world." He answered, "Why should I People are the same. They are born. They die. While they are alive, they have the same feelings. They feel love and hate, happiness and sadness, comfort and discomfort. That is why I do not want to travel. I can learn everything here. I’m going to stay home."
The man was right. He was also wrong. People are the same, but people are also different. They all have the same pattern of life—birth, youth, old age, and death. But these stages of life have different values in different cultures (文化). Also, while all people have the same feelings, the causes are different. A situation that may bring happiness in one place may not bring happiness in another place.
For example, in many countries old age is a happy time. Young people in these countries show respect to the old people. In Korea, old people are honored and respected. When they are too old to live alone, they live with a son, daughter, or other relatives.
In the United States, most old people do not live with their children or relatives. If they have enough money, they buy houses or apartments (公寓) in places where other old people live. If they are not healthy and strong enough to live alone, they live in special homes for old people. There, strangers take care of them. For them, old age is not a happy time.
So we can see that the man who stayed home was wrong. People are different in their customs and their values. In the United States, most old people are sad because ______.

A. they want to stay young but can not
B. they have to go on working to support themselves
C. they are not given enough attention
D. they cannot act like young people any longer