In the queue, the back pointer is important because:

A. without it, we would have to walk a pointer through the entire queue to get to the last node, where we enqueue
B. without it, we would have to walk a pointer through the entire queue to get to the last node, where we dequeue
C. without it, we would have memory leak when the destructor is called
D. it makes it much easier to implement the deepCopy function

A