*Question E4E10:
Which of the following can create intermittent loud roaring or buzzing AC line interference?*  

*Correct Answer is  D: All these choices are correct*  

### AI Response: (may contain errors)  

Intermittent loud roaring or buzzing AC line interference can be caused by various electrical issues. Let's break down why each choice is correct:

- **Arcing contacts in a thermostatically controlled device**:  
  When contacts in devices like thermostats arc, they can generate significant electrical noise. This noise can manifest as a roaring or buzzing sound on AC lines due to the rapid on-off switching and sparking.

- **A defective doorbell or doorbell transformer inside a nearby residence**:  
  A faulty doorbell or its transformer can cause similar interference. Transformers can produce buzzing sounds if they are malfunctioning, and this can be transmitted through the AC lines.

- **A malfunctioning illuminated advertising display**:  
  These displays often use high-voltage transformers and switching circuits, which can create electrical noise if they are not functioning correctly. This noise can also appear as roaring or buzzing on AC lines.

- **All these choices are correct**:  
  Since each of the above scenarios can independently cause the described interference, the correct answer is that all these choices are correct.

In summary, each option describes a potential source of AC line interference, and all are valid causes. Therefore, the correct answer is D: All these choices are correct.