Generics

[Mylene Morato]

Hi everybody,


I have this code:

  
import java.util.*;
public class Backlister {
//Insert here
{
List<T> output=new LinkedList<T>();
for(T t:input)
output.add(0,t);
return output;
}
}

Which of the following can be inserted at // to comile the code without error?

A. public static<T> List<T>backwards(List<T> input)
B. public static<T> List<T>backwards(List<? extends T> input)
C. public static<T> List<T>backwards(List<? super T> input)
D. public static<T> List<? extends T>backwards(List<T> input)
E. public static<T> List<? super T>backwards(List<T> input)
F. public static<? extends T> List<T>backwards(List<T> input)

The output is A,B,D,E.

I would like to know why letter B is correct instead of letter C ? Because in the code above there is a add method. I think that only List<? super T> could have a add method and not List<? extends T>.

Can anybody help me?

[Mylene Morato]

Ok.
The source is learnkey MasterExam by K & B.

[Sunny Mattas]

check here