In the developed countries, the dominant factor in the next society will be something to w

hich most people are only just beginning to pay attention: the rapid growth in the older population and the rapid shrinking of the younger generation. Politicians everywhere still promise to save the existing pensions system, but they and their constituents know perfectly well that in another 25 years people will have to keep working until their mid-70s, health permitting.

What has not yet sunk in is that a growing number of older people say those over 50 will not keep on working as traditional full-time nine-to-five employees, but will participate in the labor force in many new and different ways: as temporaries, as part-timers, as consultants, on special assignments and so on. What used to be personnel and are now known as human resources departments still assume that those who work for an organization are full-time employees. Employment laws and regulations are based on the same assumption. Within 20 or 25 years; however, perhaps as many as half the people who work for an organization will not be employed by it, certainly not on a full-time basis. This will be especially true for older people. New ways of working with people at arm's length will increasingly become the central managerial issue of employing organizations, and not just of businesses.

The shrinking of the younger population will cause an even greater upheaval, if only because nothing like this has happened since the dying centuries of the Roman Empire. In every single developed country, but also in China and Brazil, the birth rate is now well below the replacement rate of 2.2 live births per woman of reproductive age. Politically, this means that immigration will become an important and highly divisive issue in all rich countries. It will cut across all traditional political alignments. Economically, the decline in the young population will change markets in fundamental ways. Growth in family formation has been the driving force of all domestic markets in the developed world, but the rate of family formation is certain to fall steadily unless bolstered by large-scale immigration of younger people. The homogeneous mass market that emerged in all rich countries after the Second World War has been youth-determined from the start. It will now become middle-age-determined, or perhaps more likely it will split into two: a middle-age-determined mass market and a much smaller youth-determined one. And because the supply of young people will shrink, creating new employment patterns to attract and hold the growing number of older people (especially older educated people) will become increasingly important.

From the passage, which is the main influence factor in the future？

A．The influence of aging problem.

B．The shrinking of younger population.

C．The changing of working style.

D．The change of consuming pattern.