Consider a program that administers multiple-choice quizzes. For each question, the student provides a response A, B, C, or D. An X means that the student provided no answer. An example of a valid answer string is "ADXDCCDDXA". Your task is to write a method that checks whether a string is a valid answer string.

Complete the following file:

public class QuizCheck { /** Checks whether a string of quiz answers is valid. It must contain an answer A, B, C, or D for each expected answer, or an X to indicate that no answer was provided. @param input the answer string @param questions the number of questions in the string @return true if the string was valid, false otherwise */ public static boolean checkInputs(String input, int questions) { ... } }