A、About four million. B、About seven million. C、About five million. D、About six million. D信息明示题。文章第三段最后指出，一项调查最近估算出，有将近六百万的英国青年曾经

The home is the central focus of most young people’s lives in Britain, particularly for those who are still attending school. The majority rely upon their home environment as a place of security and upon their parents as the main providers of food, money and other necessities of life—as well as general advice. Young people spend a large proportion of their leisure time at home with other members of their family or with friends.
     After the home, school is the main social environment where children not only receive their formal education but also develop their identities within peer groups. All school children in Britain are encouraged to take up activities which complement their academic and vocational education and help to identify their individual talent, such as sports, drama, music and creative pursuits. Many of these form part of the school curricula.
     The personal development and informal social education of young people aged from 11 to 25 are also promoted by the Youth Service in Britain. The Service is a partnership between law authorities and a large number of voluntary organizations. A recent survey estimates that nearly six million young people in this age group are either current or past participants in the Service.
     Youth clubs and centers are the most common types of Youth Service provision, encouraging their members to participate in sport, cultural and creative activities, and community service. Some also provide information and counseling. Youth clubs may be branches of national or international bodies or they may be entirely local institutions.