A major new development in systems of work in Britain is taking place. Flexible working ho

urs, or "Flextime", are catching on fast, and this trend is continuing. In 1973, over 500 organizations had adopted the idea, and by 1974, this number had risen to over 200,000. Flexible working hours were invented in Germany in the late 1960's, but reached Britain only in 1972. The system allows workers to start and finish work whenever they want, with only two requirements. These are, firstly, that all workers must be present for certain "key" times in day, and secondly, that all workers must work an agreed total number of hours per week.

The system has proved an almost total success whenever it has been tried. A survey of 700 workers on flexible hours showed three main advantages: a beer balance between working and private life, avoidance of the need to travel during rush hours and ability to be able to finish a certain task before leaving.

From the employer's point of view, the system tends to increase productivity, reduce labour turnover and give the workers a greater sense of duty.

Flexible working hours were firstly used by the ______.

A．British

B．Americans

C．Germans

D．Japanese