All but which of the following are known to be correlated with academic achievement?

A) school composition
B) student's family background
C) teacher's verbal skills
D) student's ethnic background

Academic achievement is influenced by a variety of factors, including school composition (such as the socioeconomic status of the student body), a student's family background (including parental education and income), and a teacher's verbal skills, which can affect the quality of instruction. A student's ethnic background, in and of itself, is not a direct predictor of academic achievement; rather, the impact of ethnicity on academic outcomes is often mediated through other factors such as socioeconomic status, access to resources, and experiences of discrimination or support.