Study the diagram and answer the questions that follow :
Label the parts 1 - 4

Explanation

**Step-by-Step Solution:**

1. **Identify Part 1**: In the diagram, the first part labeled as "1" is the outermost layer of the tooth. This layer is known as the **enamel**. It is the hardest substance in the human body and protects the tooth from decay.

2. **Identify Part 2**: The second part labeled as "2" is located beneath the enamel. This layer is called the **dentine**. Dentine is less hard than enamel and contains microscopic tubules that can transmit sensations.

3. **Identify Part 3**: The third part labeled as "3" is found at the center of the tooth. This area is referred to as the **pulp**. The pulp contains nerves and blood vessels that provide nutrients to the tooth and help in sensation.

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