A parietoacanthial sinus projection (Waters method) with accurate positioning demonstrates

1. an equal distance from the lateral orbital margin to the lateral cranial cortex on both sides.
2. the bony nasal septum in alignment with the long axis of the exposure field.
3. the petrous ridges demonstrated inferior to the maxillary sinuses.
4. the ethmoid sinus through the mouth cavity in an open-mouth position.
a. 1 and 2 only
b. 3 and 4 only
c. 1, 2, and 3 only
d. 1, 2, 3, and 4

C