*Question E3B05:
Which of the following paths is most likely to support long-distance propagation on 160 meters?*  

*Correct Answer is  D: A path entirely in darkness*  

### AI Response: (may contain errors)  

On the 160-meter band, long-distance propagation is primarily supported by the ionosphere, specifically the F-layer, which is more effective at night. Here's why:

1. **Correct Answer: A path entirely in darkness**
   - At night, the D-layer of the ionosphere, which absorbs radio waves, dissipates. This allows signals to reach the higher F-layer, which can reflect them over long distances. Therefore, a path entirely in darkness is most likely to support long-distance propagation on 160 meters.

2. **Why the other choices are incorrect:**
   - **A path entirely in sunlight (Choice A):** During the day, the D-layer is present and absorbs signals on lower frequencies like 160 meters, reducing the potential for long-distance propagation.
   - **Paths at high latitudes (Choice B):** High latitude paths can be affected by auroral activity, which can disrupt radio signals and make long-distance communication less reliable.
   - **A direct north-south path (Choice C):** While not inherently bad, north-south paths are not specifically advantageous for 160 meters. The key factor is the presence of darkness, not the direction of the path.

**Rule of Thumb:**
- For low-frequency bands like 160 meters, nighttime conditions are generally more favorable for long-distance communication due to reduced absorption and enhanced ionospheric reflection.