What factor in today's economy alters the way that Super's model of career development is applied?

A) The fact that adolescents are entering the work force earlier and are contributing more to the economy than in the 20th century.
B) The fact that most young adults will have established a lifetime career by the age of 30.
C) The fact that society no longer expects people to work until retirement age.
D) The fact that job security is less reliable and that people change careers more frequently than in the past.

D