The principal growth sites of the maxilla in a downward and forward direction include the
1. frontomaxillary suture.
2. zygomaticomaxillary suture.
3. pterygopalatine suture.
4. median palatine suture.

(1) and (3)

(1) (2) (3)

(2) and (4)

(4) only.

All of the above.