According to the Textbook, Why Do Private School Students Academically

According to the textbook, why do private school students academically outperform students at public schools?

A) Private school teachers are better trained and are generally better teachers than public school teachers.
B) Teachers at private schools are more committed to the students than the teachers at private schools.
C) Because of the characteristics of the students who attend private schools.
D) Private schools have more rigorous lesson plans and are in school more days a year than public schools.