George farkas discovered that girls and asian american students receive higher grades than their academic equals because they know how to signal their teachers they are better students.

That statement is true.
According to George Farkas, Girls and Asian american students tend to behave really well in the class and really responsive toward the teacher (they asked questions, listen quietly when the teachers speak, make less trouble, etc)
This make the teacher notice them and feel inclined to give higher grades.

Ithink it's a, but i might be wrong