Wildcards

Q.

What is the output of this program?

 
    import java.util.*;
    class Output {
        public static double sumOfList(List list) {
            double s = 0.0;
            for (Number n : list)
                s += n.doubleValue();
            return s;
        }
        public static void main(String args[]) {
           List ld = Arrays.asList(1.2, 2.3, 3.5);
           System.out.println(sumOfList(ld));
        }
    }
A. 5.0
B. 7.0
C. 8.0
D. 6.0

Answer : Option B

Explanation :

None.
Output:
$ javac Output.javac
$ java Output
7.0