Read paragraph $3$ again: What is the author implying when he calls the white students "culturally disadvantaged", a term that is usually applied to undereducated minority people?

The author is not aware of how the term is usually used.

The author is implying that the students in Creston High School had not gotten a good education and had not developed good study habits. $q,$ The author is trying to be polite by using a nice word for "stupid".

$$ The author is being mildly sarcastic, applying a term to these students that they or they parents might have applied to him.