## Core Concept
Alveolar distraction osteogenesis is a surgical procedure used to increase the alveolar bone height, typically to facilitate dental implant placement. The procedure involves the controlled movement of a segment of the alveolar bone to create new bone formation. A critical factor for the success of this procedure is the availability of sufficient alveolar bone height to allow for the distraction process.

## Why the Correct Answer is Right
The adequate height of the mandible needed for alveolar distraction is generally considered to be at least **3-5 mm**. This height is necessary to ensure that there is enough bone stock to allow for the osteotomy (cutting of the bone) and the subsequent distraction process without compromising the stability of the mandible or the newly formed bone. A height of **3-5 mm** provides a sufficient amount of bone for the procedure to be successful and for the placement of dental implants afterwards.

## Why Each Wrong Option is Incorrect
- **Option A:** Less than 3 mm is generally considered inadequate for alveolar distraction because it may not provide sufficient stability for the procedure or enough bone for new bone formation.
- **Option B:** While 2-3 mm might seem borderline, it's often considered on the lower side for ensuring the success of the distraction and subsequent implant placement.
- **Option D:** More than 5 mm is not necessarily required for the procedure, making **Option C: 3-5 mm** a more specific and generally accepted range.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the success of alveolar distraction osteogenesis significantly depends on careful patient selection, including assessment of the alveolar bone height and density. The procedure is a valuable option for patients with insufficient alveolar bone for dental implant placement, offering a way to increase bone volume without the need for more extensive grafting procedures.

**Correct Answer: C. 3-5 mm.**