Suppose you want to print the value of object sl. What should you w class StudentToStr int rollno; string name; String city; Studenttostr(int rollno, String name, string city) { this.rollno-rolino; this.name-name; this.city=city; } public String toString() { return rollnot" "+name+" "+city; 1 public static void main(String args[]) { StudentToStr 31=new StudentToStr(101, "Raj","lucknow"); (2) } } 0 a. System.out.println(StudentToStr); o b. System.out.println (toString(); OC. System.out.println(si); O d. System.out.println(this.si)