- During tooth development, dentine formation begins shortly after the differentiation of odontoblasts.
- The first type of dentine to be deposited is mantle dentine.
- This is a distinct layer of dentine that forms right beneath the enamel organ and serves as the initial dentine matrix, which later mineralizes to provide the framework for further dentine deposition.

Key points to note:
- Mantle dentine is the first-formed dentine during tooth development.
- It is characterized by the presence of large collagen fibers oriented perpendicular to the dentinoenamel junction.
- Mantle dentine provides a scaffold for the subsequent formation of circumpulpal dentine.
- Circumpulpal dentine is deposited after mantle dentine and constitutes the bulk of the dentine found in mature teeth.
- Secondary dentine starts forming after root formation is complete and continues throughout life, helping to protect the pulp.
- Predentine is the unmineralized organic matrix secreted by odontoblasts before it mineralizes to become dentine.

Therefore, the correct answer is Mantle dentine, as it represents the initial dentine layer deposited during tooth development.

Reference: Ten Cate's Oral Histology, 9th Edition, Chapter 4: Dentin and Pulp / Page 97