The author holds that graduate student is a safe and familiar form for young people because________.‎‌‎
选项：

A:it can help the young people to lead a better life.
B:it is a provisional form for the young people to prove themselves competent in society and intensely aware of being on trial as well.
C:it is the familiar school life for the young people.
D:the young people can learn more knowledge to prepare for their future job.