*Question E1F04:
[97.3] Which of the following geographic descriptions approximately describes "Line A"?*  

*Correct Answer is  A: A line roughly parallel to and south of the border between the US and Canada*  

### AI Response: (may contain errors)  

"Line A" is a regulatory boundary defined by the FCC to manage radio frequency interference between the United States and Canada. Here's a breakdown of the question and the choices:

1. **Correct Answer: A line roughly parallel to and south of the border between the US and Canada**

   - **Explanation**: "Line A" is a specific line that runs approximately parallel to the US-Canada border. It is used to delineate areas where certain radio operations are restricted to prevent interference with Canadian communications. This line is important for managing cross-border frequency use and ensuring that radio services in the US do not interfere with those in Canada.

2. **Why the other choices are incorrect**:

   - **Choice B: A line roughly parallel to and west of the US Atlantic coastline**
     - This description does not relate to "Line A." There is no regulatory line known as "Line A" that runs parallel to the Atlantic coastline.

   - **Choice C: A line roughly parallel to and north of the border between the US and Mexico**
     - This is incorrect because "Line A" is not associated with the US-Mexico border. The US-Mexico border has its own set of regulations and agreements, but "Line A" specifically pertains to the US-Canada border.

   - **Choice D: A line roughly parallel to and east of the US Pacific coastline**
     - Similar to choice B, this does not describe "Line A." There is no such regulatory line parallel to the Pacific coastline referred to as "Line A."

Understanding "Line A" is important for amateur radio operators, especially those operating near the US-Canada border, as it affects frequency allocations and usage to prevent cross-border interference.