The number of teeth that grow twice in human life is

Options

A. 4
B. 12
C. 20
D. 28

Answer

To determine the number of teeth that grow twice in human life, we can follow these steps:

1. **Identify the Types of Teeth**: Humans have two sets of teeth in their lifetime: primary (or temporary) teeth and permanent (or adult) teeth.

2. **Count the Primary Teeth**: The primary teeth, commonly known as baby teeth, consist of 20 teeth. These teeth begin to erupt around the age of 6 months and typically fall out starting around age 6.

3. **Count the Permanent Teeth**: The permanent teeth replace the primary teeth. Adults usually have 32 permanent teeth, including the wisdom teeth.

4. **Determine Which Teeth Grow Twice**: Since primary teeth are replaced by permanent teeth, we can conclude that the primary teeth (20 in total) are the ones that grow twice in a person's life.

5. **Final Answer**: Therefore, the number of teeth that grow twice in human life is 20.