The remove() method in the Queue interface ________.
◦ retrieves, but does not remove, the head of this queue, returning null if this queue is empty
◦ retrieves and removes the head of this queue, or null if this queue is empty
◦ retrieves and removes the head of this queue and throws an exception if this queue is empty
◦ retrieves, but does not remove, the head of this queue, throwing an exception if this queue is empty