Write a C# program for a computer science class offered in ABC University. In this class, some students are undergraduate students and some students are graduate students. The grading policies are: a). There are two quizzes. The full grade of each quiz is 10 points. b). There is one midterm and one final . The full grade of the final is 50 points. The full grade of the midterm is 100 points. c). For a undergraduate student, the final counts for 50% of the grade, the midterm counts for 30%, and the two quizzes together count for a total of 20% (10% for each quiz). d). For a graduate student, the final counts for 40% of the grade, t he midterm counts for 20%, and the two quizzes together count for a total of 40% (20% for each quiz). For a undergraduate student, any grade of 90 or more is an A, any grade of 80 or more (but less than 90) is a B, any grade of 70 or more (but less than 80) is a C, any grade of 60 or more (but less than 70) is a D, and any grade below 60 is an F. For a graduate student, any grade of 90 or more is an A, any grade of 80 or more (but less than 90) is a B, any grade of 70 or more (but less than 80) is a C, any grade below 70 is an F. Define and use a structure for the student record including the grade of each quiz and the grade of each test. Define an enumeration having 4 symbols for the letter grade. That is, letter A stands for 90, letter B stands for 80, letter C stands for 70, and letter D stands for 60. Define an abstract class Student standing for the students taking this class. It has four private fields and two abstract methods. The private fields are reset or retrieved via an indexer. - Private fields are: ID, Name, Major, Email - Abstract methods are: - Method 1: when implemented in a derived class, it will calculate the students numeric grade for the entire course - Method 2: when implemented in a derived class, it will calculate the final letter grade Define a derived class UnderGraduate that has one field standing for the class status (freshman, sophomore, junior, or senior) of a student and one method that will print the following information: 4 fields from the abstract class, The class status of a student; The numeric grade for the entire class, The letter grade for the entire class. In addition, the derived class will implement two abstract methods defined in the class Student . Define a derived class Graduate that has two fields standing for the thesis title and supervisor name of a graduate student and one method that will print the following information: 4 fields from the abstract class, The thesis title, The supervisor name, The numeric grade for the entire class, The letter grade for the entire class. In addition, the derived class will implement two abstract methods defined in the class Student