*Question E1B02:
[97.307(f)(2)] Which of the following is an acceptable bandwidth for digital voice or slow-scan TV transmissions made on the HF amateur bands?*  

*Correct Answer is  A: 3 kHz*  

### AI Response: (may contain errors)  

In the context of the FCC regulations for amateur radio, particularly for digital voice or slow-scan TV (SSTV) transmissions on the HF bands, bandwidth limitations are set to ensure efficient use of the spectrum and to minimize interference.

### Explanation:

1. **Correct Answer: 3 kHz (Choice A)**
   - **Why it's correct:**  
     The FCC rules specify that the maximum bandwidth for digital voice or slow-scan TV transmissions on the HF amateur bands is 3 kHz. This limitation is in place to ensure that these transmissions do not occupy excessive bandwidth, which could interfere with other users on the HF bands.

2. **Why the other choices are incorrect:**
   - **10 kHz (Choice B):**  
     A 10 kHz bandwidth is too wide for HF digital voice or SSTV transmissions. Such a wide bandwidth could cause interference with adjacent channels and is not compliant with the FCC's 3 kHz limit for these types of transmissions.
   - **15 kHz (Choice C):**  
     Similar to 10 kHz, a 15 kHz bandwidth is far beyond the acceptable limit for HF digital voice or SSTV. It would lead to significant interference issues and is not allowed under FCC regulations.
   - **20 kHz (Choice D):**  
     A 20 kHz bandwidth is even wider and would cause even more interference. It is not permissible for HF digital voice or SSTV transmissions according to the FCC's 3 kHz bandwidth restriction.

### Useful Rule of Thumb:

- **Bandwidth Limitation:**  
  For digital voice and SSTV on HF bands, always remember the 3 kHz rule. This is a key regulation to ensure efficient and interference-free operation within the amateur radio HF spectrum.

By adhering to the 3 kHz bandwidth limit, amateur radio operators help maintain orderly and efficient use of the HF bands, minimizing interference with other users.