doubt abt Generics mock question - from K&B

[adam Lui]

Given a method declared as:

 public static <E extends Number> List<? super E> process(List<E> nums)

A programmer wants to use this method like this:

// INSERT DECLARATIONS HERE
output = process(input);

Which pairs of declarations could be placed at // INSERT DECLARATIONS HERE to allow the code to compile? (Choose all that apply.)
A. ArrayList<Integer> input = null;
ArrayList<Integer> output = null;
B. ArrayList<Integer> input = null;
List<Integer> output = null;
C. ArrayList<Integer> input = null;
List<Number> output = null;
D. List<Number> input = null;
ArrayList<Integer> output = null;
E. List<Number> input = null;
List<Number> output = null;
F. List<Integer> input = null;
List<Integer> output = null;
G. None of the above.

the answers are B, E and F.

as if B is "ArrayList<Integer> input = null",
WHY would process(input) works, as the method's parameter declared as process(List<E> nums), type of List not ArrayList?

[Burkhard Hassel]

Because

import java.util.*;
 
class Main {
public static void main(String[] args) {
ArrayList ali = new ArrayList();
System.out.println(ali instanceof List);
}
}

Bu.