*Question E3B01:
Where is transequatorial propagation (TEP) most likely to occur?*  

*Correct Answer is  A: Between points separated by 2,000 miles to 3,000 miles over a path perpendicular to the geomagnetic equator*  

### AI Response: (may contain errors)  

Transequatorial propagation (TEP) is a unique radio propagation phenomenon that occurs under specific conditions. Let's break down the correct answer and why the other options are not suitable.

### Correct Answer: 
**A: Between points separated by 2,000 miles to 3,000 miles over a path perpendicular to the geomagnetic equator.**

#### Explanation:
- TEP is most effective when signals travel between points that are approximately 2,000 to 3,000 miles apart, specifically along paths that are perpendicular to the geomagnetic equator. 
- This is due to the way the ionosphere behaves in relation to the Earth's magnetic field, allowing for enhanced signal propagation during certain times, particularly around the equinoxes.

### Why the Other Choices are Incorrect:

- **B: Between points located 1,500 miles to 2,000 miles apart on the geomagnetic equator.**
  - This distance is too short for TEP to be effective. TEP typically requires longer distances (2,000 to 3,000 miles) to take advantage of the ionospheric conditions.

- **C: Between points located at each other’s antipode.**
  - Antipodal points are directly opposite each other on the globe, which does not align with the specific conditions required for TEP. TEP is more about the angle and distance relative to the geomagnetic equator rather than being directly opposite.

- **D: Through the region where the terminator crosses the geographic equator.**
  - The terminator is the dividing line between day and night on Earth. While it affects propagation, TEP is specifically related to the geomagnetic equator and the distances mentioned, not the terminator's position.

### Summary:
- TEP is best observed over distances of 2,000 to 3,000 miles, perpendicular to the geomagnetic equator, due to favorable ionospheric conditions. Understanding these distances and the geomagnetic context is crucial for recognizing TEP's characteristics in radio communications.