In humans vestige of the tail is made up of four fused bones. This structure is known as:

Options

A. sacrum
B. coccyx LED
C. sternum
D. centrum

Explanation

To answer the question regarding the vestige of the tail in humans made up of four fused bones, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Vestigial Structures**:
- Vestigial structures are remnants of organs or parts that had a function in an early ancestor but have lost most or all of their original function in a later species.

2. **Identifying the Structure**:
- In humans, the vestigial structure that corresponds to the tail is known as the coccyx.

3. **Composition of the Coccyx**:
- The coccyx is made up of four fused bones. It is often referred to as the "tailbone."

4. **Developmental Aspect**:
- During human embryonic development, a tail-like structure can be observed for a brief period (approximately from the 14th to the 22nd week of gestation), which eventually regresses to form the coccyx.

5. **Comparison with Other Structures**:
- It's important to differentiate the coccyx from other structures:
- **Sacrum**: A triangular bone formed by the fusion of five vertebrae (S1 to S5).
- **Sternum**: Also known as the breastbone, located in the center of the chest.
- **Centrum**: Refers to the central part of a vertebra.

6. **Conclusion**:
- Therefore, the correct answer to the question is that the vestige of the tail in humans, made up of four fused bones, is known as the **coccyx**.

### Final Answer:
The structure is known as the **coccyx**.

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