Research Suggests That Tracking Has All but Which One of the Following

Research suggests that tracking has all but which one of the following effects?

A) Low-track students are less likely to develop positive self images.
B) Poor and minority students are more likely to be placed in lower tracks.
C) Low-track students are given higher quality instruction in order to encourage movement into a higher track.
D) Placement in a college preparatory track had positive effects on academic achievement regardless of family background or ability.