(单选题)12: My father was 17 when he left the farm in Cameron,N.C., and set off for Baltimore to apply for a job at the Martin Aircraft Company. When asked what he wanted to do, he said,"Everything." He explained that his goal was to learn every job in the factory. He＇d like to go to a department and find out what was done there. When the supervisor determined his work was as good as anyone else＇s, he＇d want to go to a different department and start over. The personnel people agreed to this unusual request, and by the time H.T.Morris was 20, he＇d made his way through the huge factory and was working in experimental design for a fantastic salary. Whenever he went to a new department, he looked for the guys who had been around forever. These were the people novices usually avoided, afraid that next to them they＇d look like the beginners they were. My father asked them every question he could think of. They liked this inquisitive young man and showed him shortcuts they had developed that no one else had ever asked about. These sages became his mentors. Whatever your goals, plan to network with those who know more than you. Model your efforts on theirs, adjusting and improving as you go. 问题：It took the author＇s father about ( ) years to be able to do every job in the big factory.

A: two

B: three

C: five

D: six