In a healthy periodontium, attached gingiva
1. is bound firmly by the periosteum to the alveolar bone.
2. is attached by collagen fibres to the cementum.
3. displays varying degrees of stippling.
4. has a keratinized surface.

All of the above

(1) (2) (3)

(1) and (3)

(2) and (4)

(4) only