A vestigial tooth is

Options

A. Incisor
B. Molar
C. Premolar
D. Canine

Answer

### Step-by-Step Solution:

1. **Understanding Vestigial Organs**:
- A vestigial organ is one that has lost its original function through the course of evolution. In humans, these organs may still be present but do not serve the purpose they once did in our ancestors.

2. **Identifying the Types of Teeth**:
- The question provides four options: incisor, molar, premolar, and canal.
- Incisors are used for cutting food, premolars are used for grinding food, and canines are used for tearing food.

3. **Focusing on Wisdom Teeth**:
- Among the teeth types, the wisdom teeth (or third molars) are known to be vestigial. They were useful for our ancestors who had larger jaws and needed more teeth to grind down plant material.

4. **Evolutionary Perspective**:
- As human diets evolved and became softer, the need for larger jaws and more teeth decreased. Consequently, the jaw size reduced, but the third molars still develop in many people, even though they often do not serve a functional purpose anymore.

5. **Conclusion**:
- Based on the above analysis, the correct answer to the question "A vestigial tooth is" is option B: molar (specifically referring to the wisdom teeth).

### Final Answer:
A vestigial tooth is a molar, specifically the wisdom tooth.

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