Which of the following has definite length?

Options

A. a line
B. a ray
C. a line segments
D. none of these

Answer

To determine which of the following has a definite length, we need to analyze each option provided: line, ray, line segment, and none of these.

### Step-by-Step Solution:

1. **Understanding the Concept of Definite Length**:
- Definite length means a length that can be measured.

2. **Analyzing the First Option: Line**:
- A line is defined as a straight path that extends infinitely in both directions.
- Since a line has no endpoints, it cannot be measured.
- **Conclusion**: A line does not have a definite length.

3. **Analyzing the Second Option: Ray**:
- A ray starts at a point and extends infinitely in one direction.
- Similar to a line, a ray has no endpoint on one side, making it impossible to measure its length.
- **Conclusion**: A ray does not have a definite length.

4. **Analyzing the Third Option: Line Segment**:
- A line segment is a part of a line that is bounded by two distinct endpoints.
- The length of a line segment can be measured as it has a definite starting point and ending point.
- **Conclusion**: A line segment has a definite length.

5. **Final Conclusion**:
- Among the options provided, the only one that has a definite length is the line segment.

### Answer:
The option that has a definite length is **line segment**.