In 2019, the Educational Testing Service (ETS) Charged $64

In 2019, the Educational Testing Service (ETS) charged $64.50 to take the Scholastic Aptitude Test (SAT) but $205 to take the Graduate Record Exam (GRE) . One reason for this difference in price is

A) more people took the SAT than the GRE in 2019.
B) the GRE is a longer test with more questions.
C) an average, those who take the GRE have higher incomes than those who take the SAT.
D) the ETS faces competition in the market for the SAT but no competition for the GRE.