In the early fifties, only eight or nine out of a hundred young men changed their jobs within the first three years with the company. In the past few years, almost thirty-five percent of the college-graduated work force changed jobs within the same period. These people want to intensify their management training. Since most jobs take only a year to a year and a half to master, in order to continue learning, they have to make a job change. Even company presidents tend to be seen as mobile specialists, staying with one company an average of only five years.
Company presidents in the United States today tend to be young men who begin their careers with educational backgrounds in engineering science, or business management. They have worked for a few years as technical specialists and quickly moved into higher management positions. Most of them were making ＄ 30 000 per year by the time they reached thirty. On an average, these men have only twenty years working experience at management level when they become company presidents. On the way to the top, they have an average of eleven promotions and seven city transfers.
Friendships remain casual and are usually derived from business contracts. Families of these career men have little time to put down roots in and become part of a community.
In the past, a few men attained high positions through family and social connections; today, high positions go to men who are mobile, and have good educational, backgrounds.
According to the passage, an increasing number of future company presidents might be ______.

A. people who have spent a number of years with one company
B. young people who do not want to move often, but are steady and dependable
C. people who have spent a long time concerned with community affairs
D. young people who have good education and are willing to move around