Which of the following statement is/are true regarding light curing of a composite resin?
1. The curing tip should be within 2mm of the material.
2. Light intensity is inversely proportional to the distance from the material.
3. A darker shade of material requires longer curing time.
4. Curing of composite resin cannot occur through enamel.

(4) only

(1) (2) (3)

(1) and (3)

(2) and (4)

All of the above