*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)  

To understand why "A path entirely in darkness" is the correct answer for long-distance propagation on 160 meters, let's break down the options:

### Correct Answer: A path entirely in darkness
- **Explanation**: 
  - At lower frequencies like 160 meters (1.8 MHz), radio waves can reflect off the ionosphere, which is influenced by the time of day. 
  - During nighttime, the ionosphere is more conducive to long-distance propagation because the D layer (which absorbs lower frequency signals during the day) diminishes, allowing signals to reflect off the E and F layers more effectively.
  - Therefore, paths that are entirely in darkness are more likely to support long-distance communication.

### Why the other choices are incorrect:
- **A: A path entirely in sunlight**  
  - **Explanation**: During the day, the D layer is more active and absorbs lower frequency signals, making long-distance propagation less effective. This is not ideal for 160 meters.

- **B: Paths at high latitudes**  
  - **Explanation**: While high latitudes can experience unique propagation conditions, they are not necessarily optimal for long-distance communication on 160 meters. The ionosphere's behavior can be unpredictable, and paths may not be as reliable.

- **C: A direct north-south path**  
  - **Explanation**: The direction of the path (north-south) does not inherently affect propagation on 160 meters. What matters more is the time of day and the ionospheric conditions, which are better at night.

### Summary
- For long-distance propagation on 160 meters, nighttime conditions are crucial due to the reduced absorption by the D layer. Thus, a path entirely in darkness is the most favorable for effective communication.

### Useful Rule of Thumb
- **Nighttime Propagation**: Lower frequency bands (like 160 meters) are best for long-distance communication during nighttime due to the ionosphere's behavior.