Which sentence reflects the central idea of the passage?

Standardized testing of students refers to all students being given the same test or kind of test. This kind of testing is often harmful to the students. It also places too much importance on the student’s performance on the day of the test. This also means that the overall growth of the student is neglected. Studies have shown that standardized testing causes an increased level of stress in both students and teachers, and many teachers resort only to teaching the tests. This limits the child’s potential. Standardized testing also does not take into account the backgrounds of the students taking the tests.