Which of the Following Reasons Best Explains Why U

Which of the following reasons best explains why U.S. students fall behind in academic accomplishments compared to their international peers?

A) Instruction in the United States is less challenging than in other countries.
B) U.S. teachers assign less homework than teachers in other countries.
C) U.S. parents tend to be disinterested in their children's education.
D) U.S. students have language deficits that compound reading and math problems.