Why Does Tracking Persist, Even Though It Clearly Segregates Students

Why does tracking persist, even though it clearly segregates students by social class and ethnicity?

A) Privileged parents feel that tracking gives their children educational benefits.
B) Tracking by ability group increases teachers' perceptions of what grades are appropriate for students in different tracks.
C) Movement toward detracking has never gained much support.
D) Many teachers prefer to manage classrooms with a range of student abilities.