The method iterator begin() returns an iterator representing the position: O of the element before the first element in the container. of the first element in the container. O of the element after the first element in the container. O of the header node. Question 19 Which of the following is true for the array based queue implementation: enqueuel) takes O(n), dequeue() takes O(1). enqueue() takes 0(1), dequeue() takes O(1). enqueuel) takes O(n), dequeue() takes O(n). O none of the above