Independent Measures of Achievement,such as SAT Scores,have Not Risen in the Past

Independent measures of achievement,such as SAT scores,have not risen in the past decade,but overall grades in school have risen over that same period.What is the most likely explanation for this outcome?

A) Student performance in school has changed for the better,and the students are demonstrating greater achievement.
B) Student performance in school has improved,but only because students are cheating more often on tests.
C) Instructors have become more lenient,awarding higher grades for the same performance,which is known as grade inflation.
D) Independent measures of achievement such as the SAT are harder than they were a decade ago.