The following match method is intended to remove all elements divisible by key from an ArrayList of integers. The removed elements are added to a new ArrayList, which the method returns.

public static ArrayList<Integer> match(ArrayList<Integer> numList, int key)
{
    ArrayList<Integer> returnList = new ArrayList<Integer>();
    int i = 0;
    while (i < numList.size())
    {
        int num = numList.get(i);
        if (num % key == 0)
        {
            numList.remove(i);
            returnList.add(num);
        }
        i++;
    }
    return returnList;
}

For example, if numList contains [5, 2, 10, 20, 16] and key is 5, the method is expected to modify numList to [2, 16] and return an ArrayList containing [5, 10, 20].

Which of the following statements best explains why the method does not always work as intended?