81. In order to encourage children to get good grades in school, many parents educate their children like this: "In school, you always use academic achievements to judge the pros and cons. You either have good grades or poor grades. In the teacher's eyes, you are either good Students are either poor students. Since all students with good academic performance are good students in the teacher's eyes, every student with poor academic performance is a poor student in the teacher's eyes. ". In order for the parent's argument to be valid, which of the following assumptions must be true? ['At school, academic performance is not the only indicator of student strength.', 'Teachers have the ability to distinguish between good and bad students.', 'n the eyes of the teacher, students with good academic performance may not be good students.', 'In the eyes of the teacher, a good student is a good student.']