Which of the following is not a polygon?

Options

A.
B.
C.
D.

Answer

To determine which of the given options is not a polygon, we need to understand the definition of a polygon and analyze each option accordingly.

### Step-by-Step Solution:

1. **Understand the Definition of a Polygon**:
- A polygon is a closed figure made up of straight line segments. The line segments must connect at their endpoints, and they cannot cross each other.

2. **Examine Each Option**:
- **Option 1**: Check if it is a closed figure made of straight lines.
- **Option 2**: Check if it is a closed figure made of straight lines.
- **Option 3**: Check if it is a closed figure made of straight lines.
- **Option 4**: Check if it is a closed figure made of straight lines.

3. **Analyze Option 1**:
- If Option 1 is a triangle (3 sides), it is a closed figure made of straight lines. Therefore, it is a polygon.

4. **Analyze Option 2**:
- If Option 2 is a quadrilateral (4 sides), it is also a closed figure made of straight lines. Therefore, it is a polygon.

5. **Analyze Option 3**:
- If Option 3 is a curve or a straight line, it does not form a closed figure made of straight lines. Therefore, it is **not a polygon**.

6. **Analyze Option 4**:
- If Option 4 has multiple sides and is a closed figure made of straight lines, it is a polygon.

7. **Conclusion**:
- Based on the analysis, the option that is not a polygon is **Option 3**.

### Final Answer:
**Option 3 is not a polygon.**

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