According to the Textbook, Why Are Schools Unsuccessful in Overcoming

According to the textbook, why are schools unsuccessful in overcoming social class differences?

A) because there are differences in intelligence and ability between classes
B) because people are more comfortable remaining with their own class
C) because students are assigned to differing educational experiences based on their perceived intelligence
D) because many extracurricular educational opportunities cost money and are available to people based on ability to pay