Which of the following is not a function of human skeleton?

Options

A. Movement
B. Protection of internal organs
C. Formation of blood cells
D. Reproduction

Explanation

### Step-by-Step Solution:

1. **Identify the Functions of the Human Skeleton**: The human skeleton has several important functions, including:
- **Movement**: The skeleton provides a framework that supports movement through the attachment of muscles.
- **Protection**: It protects vital internal organs such as the heart, lungs, and brain.
- **Blood Cell Formation**: The bone marrow within the skeleton is responsible for producing blood cells.

2. **Analyze the Given Options**: The question asks which of the following is NOT a function of the human skeleton. The options typically include:
- Movement
- Protection of internal organs
- Formation of blood cells
- Reproduction

3. **Evaluate Each Option**:
- **Movement**: This is a function of the skeleton as it aids in locomotion.
- **Protection of Internal Organs**: The skeleton protects vital organs, making this a function.
- **Formation of Blood Cells**: The skeleton is involved in the production of blood cells, so this is also a function.
- **Reproduction**: The skeleton does not play a role in reproduction; this is primarily the function of reproductive organs such as ovaries and testes.

4. **Conclusion**: Since reproduction is not a function of the human skeleton, it is the correct answer to the question.

### Final Answer:
The option that is NOT a function of the human skeleton is **Reproduction**.

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