How many teeth in man grows twice is life:

Options

A. 32
B. 28
C. 20
D. 12

Answer

To solve the question "How many teeth in man grow twice in life?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks how many teeth in humans grow twice during their lifetime. This refers to the sets of teeth that humans develop.

2. **Identifying the Sets of Teeth**: Humans have two sets of teeth:
- **Primary Teeth**: Also known as milk teeth or baby teeth.
- **Permanent Teeth**: Also known as secondary teeth.

3. **Counting Primary Teeth**:
- Primary teeth typically consist of 20 teeth in total. This includes:
- 10 in the upper jaw (maxilla)
- 10 in the lower jaw (mandible)
- The dental formula for primary teeth is 2-1-0-2 for each quadrant, which totals to 20 teeth (4 incisors, 2 canines, and 4 molars).

4. **Counting Permanent Teeth**:
- After losing primary teeth, humans develop permanent teeth, which usually total 32 teeth. However, the question specifically asks about teeth that grow twice, which refers only to the primary teeth.

5. **Conclusion**: Since primary teeth are replaced by permanent teeth, the total number of teeth that grow twice in a human's life is the number of primary teeth, which is 20.

### Final Answer:
The number of teeth in man that grow twice in life is **20**.

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