Fatima was born to a lower class family in rural Pennsylvania. After taking a job in the mail room of a large corporate office, Fatima is slowly promoted through the ranks and becomes CEO of the company by the age of 50. At the same time, Fatima's brother and sister worked in jobs very similar to their parents. Fatima's experience is an example of ______. Group of answer choices A caste system A closed system Intragenerational mobility Structural mobility