How we look and how we appear to others probably worries us more when we are in our teens or early twenties than at any other time in our life. Few of us are content to accept ourselves as we are, and few are brave enough to ignore the trends of fashion. Most fashion magazines or TV advertisements try to persuade us that we should dress in a certain way or behave in a certain manner. If we do, they tell us, we will be able to meet new people with confidence and deal with every situation confidently and without embarrassment. Changing fashion, of course, does not apply just to dress. A barber today does not cut a boy's hair in the same way as he used to, and girls do not make up in the same way as their mothers and grandmothers did. The advertisers show us the latest fashionable styles and we are constantly under pressure to follow the fashion in case our friends think we are odd or dull. What causes fashions to change? Sometimes convenience or practical necessity or just the fancy of an influential person can establish a fashion. Take hats for example. In cold climates, early buildings were cold inside, so people wore hats indoors as well as outside. In recent times, the late President Kennedy caused a depression in the American hat industry by not wearing hats, and more American men followed his example. There is also a cyclical  pattern in fashion. In the 1920s in Europe and America, short skirts became fashionable. After World War II, they dropped to ankle length. Then they got shorter and shorter until the miniskirt was in fashion. After a few more years, skirts became longer again. Today, society is much freer and easier than it used to be. It is no longer necessary to dress like everyone else. Within reason, you can dress as you like or do your hair the way you like instead of the way you should because it is the fashion. The popularity of jeans and the "untidy" look seems to be a reaction against the increasingly expensive fashion of the top fashion houses. At the same time, appearance is still important in certain circumstances and then we must choose our clothes carefully. It would be foolish to go to an interview for a job in a law firm wearing jeans and a sweater, and it would be discourteous  to visit some distinguished scholar looking as if we were going to the beach or a night club. However, you need never feel depressed if you don't look like the latest fashion photo. Look around you and you'll see that no one else does either! According to the passage, we care about our appearance most in the age period of  _  .
10-20 10-25 20-25 20-30