Which of the following depicts the usual order of extraction of teeth, if serial extraction is chosen as the treatment to alleviate severe crowding?

Primary canines are extracted to encourage alignment of the crowded incisors. However, the incisors align and upright, borrowing space otherwise needed for eruption of the permanent canine. Primary first molars are then extracted to encourage eruption of the first premolar, so it may be extracted to make room for the permanent canine to erupt. Note: Primary second molars and permanent canines are not extracted during serial extraction.