A、All applicants in US have to take it. B、It is the only college entrance test in US. C、It helps to measure applicants’ academic

A growing number of American universities are dropping the entrance exam requirement. More than 800 universities now allow students to apply without an SAT or ACT test score. The SAT and ACT are the two major college entrance tests in the United States.
For years, colleges have used these tests to help measure an applicant’s academic skills. But more universities are becoming "test optional." Students who apply to test-optional schools can choose whether they want to include test scores in their applications.
    George Washington University in Washington, D.C. is one of the latest schools to adopt a test-optional admissions policy for most of its applicants. It is the largest private university to drop the test requirement. Karen Stroud Felton is the Dean of Admissions at George Washington University. She said in a statement that the university "had concerns that students who could be successful... felt discouraged from applying if their scores were not as strong as their high school performance."
    Each of America’s more than 3,000 colleges and universities has its own admission requirements. At some colleges, test scores are very important. Others are more interested in an applicant’s life experience, teacher recommendations, community service, and talents.
High school GPA, or grade point average, is another way to judge a student’s ability. A GPA of 3.5 or higher (on scale from 0 to 4) is considered good.     For international applicants, universities have specialists review the academic standards of different countries and convert them to GPA equivalents.
    Jennifer Tkacz is the Director of International Admissions at George Mason University. It is the largest test-optional university in the United States. She explains why the school went test-optional in 2012.
    "The university administration felt that for many students, their test scores aren’t necessarily a reflection of their academic strength and the GPA is a much better indicator." Ms. Tkacz says high school performance says more about a student’s potential than a test score.
    "Generally, a strong curriculum that prepares students for college we feel is a much better indicator of how they will succeed. They’ve been in the classroom, they’ve been taking challenging coursework, they’ve been applying that coursework to tests, writing papers, and participating in classroom work. And we think reviewing that information would give us a better idea of how they would perform here at Mason—versus sitting down one day, one time, taking a test."
19.What do we learn about SAT?
20.What does "test optional" mean?
21.What do we learn about George Mason University?