2.1 get correct answer

src/main/java/org/example/Main.java

src/main/java/org/example/answerSheet/AnswerSheet.java

src/main/java/org/example/answerSheet/answer/Answer.java

src/main/java/org/example/exam/Exam.java

src/main/java/org/example/exam/ExamFactory.java

src/main/java/org/example/exam/JsonExam.java

src/main/java/org/example/exam/XmlExam.java

src/main/java/org/example/grader/Grader.java

...ain/java/org/example/question/MultipleChoiceQuestion.java

src/main/java/org/example/question/ProgrammingQuestion.java

src/main/java/org/example/question/QuestionFactory.java

src/main/java/org/example/question/SingleChoiceQuestion.java

src/main/java/org/example/question/sample/Sample.java