Mucosal thickening in the maxillary sinus
1. may fill the entire air space of the sinus.
2. is often usually an incidental radiographic finding.
3. may be caused by a periapical infection.
4. may be associated with nasal discharge.

All of the above.

(1) (2) (3)

(4) only

(2) and (4)

(1) and (3)