Which conclusion is BEST supported by the data in the graph?

A) Over the years, schools have succeeded in consistently lowering dropout rates for all students.
B) Schools must do more to lower dropout rates, especially for African-American and Hispanic students.
C) Schools have worked hard to keep dropout rates lower for African-American and Hispanic students than for white students.
D) After dropout rates reached a peak in 2000, schools worked harder to help students from all ethnic backgrounds graduate from high school.