*Question E1D04:
[97.119(a)] Which of the following is required in the identification transmissions from a balloon-borne telemetry station?*  

*Correct Answer is  A: Call sign*  

### AI Response: (may contain errors)  

In the context of balloon-borne telemetry stations, the identification requirements are governed by FCC regulations. 

1. **Why the correct answer is correct:**
   - The correct answer is **A: Call sign**. According to FCC rules, all amateur radio stations, including balloon-borne telemetry stations, must transmit their assigned call sign at regular intervals. This is essential for identification purposes and to comply with licensing regulations.

2. **Why the other choices are incorrect:**
   - **B: The output power of the balloon transmitter**: While it's important for operators to know the output power for operational reasons, it is not a requirement to include this information in identification transmissions.
   - **C: The station's six-character Maidenhead grid locator**: Similar to the output power, while the grid locator can be useful information for operators and may be included in some transmissions, it is not a mandatory part of the identification process.
   - **D: All these choices are correct**: This option is incorrect because only the call sign is required for identification, making this choice invalid.

3. **Useful rules of thumb:**
   - Always include your call sign in any transmission to comply with FCC regulations.
   - Familiarize yourself with the specific requirements for different types of stations, as they may vary.

In summary, the only mandatory element for identification from a balloon-borne telemetry station is the call sign, making option A the correct choice.