Given below Java program public class Test02 ( JUST protected int b; protected [?] class Test02A { private int a; public static void main(String[] args) 9399 Test02A test 02a= new Test02A(); test02a.a = 0; System.out.println (test02a.a); What need to replace [?] to make the above program to be compiled? A. volatile B. synchronized C. static D. visible 2. N