Which of the following factors influence(s) the development of root caries?
1. A diet high in refined carbohydrates.
2. Periodontal disease.
3. The anatomy of the cemento-enamel junction.
4. Xerostomia.

All of the above.

(4) only

(2) and (4)

(1) and (3)

(1) (2) (3)