**Question:** Which of the following is least mineralized?

A. Dentin
B. Enamel
C. Vertebral body
D. Phalanx

**Core Concept:** Mineralization in vertebrates involves the deposition of inorganic substances, primarily calcium phosphate, within the extracellular matrix of tissues. In this context, mineralization refers to the extent of inorganic material present in the tissue.

**Why the Correct Answer is Right:** Dentin is the least mineralized option among the given choices. Dentin is an organic matrix rich in collagen fibers that serves as a scaffold for mineralization. Although dentin contains calcium phosphate, the mineral content is less than that of enamel and vertebral bodies.

**Why Each Wrong Option is Incorrect:**

**Option A (Dentin):** As mentioned earlier, dentin contains calcium phosphate but has lower mineral content compared to enamel and vertebral bodies.

**Option B (Enamel):** Enamel is the hardest tissue in the human body, primarily composed of hydroxyapatite crystals. This makes enamel the most mineralized option among the choices.

**Option C (Vertebral body):** Vertebral bodies are composed of bone tissue, which is mineralized due to the presence of hydroxyapatite crystals. However, the mineral content in vertebral bodies is less than that of enamel.

**Option D (Phalanx):** Phalanx is a bone segment, primarily found in the hands and feet, which is also mineralized due to hydroxyapatite crystals. Like vertebral bodies, phalanx has lower mineral content compared to enamel.

**Correct Answer:** B. Enamel