According to the text, why does the writer think it is not likely that a bag-lady mother would be present at her children’s graduation? ___
A、Because the invitation is only extended to the parents of top students.
B、Because the mother is probably not available at the time when she is busy with her work.
C、Because their children would think having a poor mother is a stigma which is detrimental to their future career development.
D、Because the mother, disappointed with the college educational system, might refuse to attend the ceremony,