One of the Most Interesting Findings from the Coleman Report

One of the most interesting findings from the Coleman Report was that:

A) when upper-status students went to school with fewer lower-class students, their grades fell.
B) when lower-class students went to school with more upper-status students, their grades improved.
C) when males and females were separated in classes, both groups' grades improved.
D) when all students were on vacation during the summer, they all lost ground with regard to knowledge.