*Question G4C01:
Which of the following might be useful in reducing RF interference to audio frequency circuits?*  

*Correct Answer is  B: Bypass capacitor*  

### AI Response: (may contain errors)  

To reduce RF interference to audio frequency circuits, the correct answer is a bypass capacitor. Here's why:

### Correct Answer: Bypass Capacitor
- **Function**: A bypass capacitor is used to shunt high-frequency noise (RF interference) to ground, effectively filtering it out from the audio frequency circuit. 
- **Operation**: It provides a low-impedance path for high-frequency signals, allowing them to bypass the audio circuit while letting the desired audio frequencies pass through.

### Why Other Choices Are Incorrect:
- **A: Bypass Inductor**  
  - **Function**: A bypass inductor would block high-frequency signals and allow low-frequency signals to pass. This is the opposite of what is needed for reducing RF interference.
  
- **C: Forward-biased Diode**  
  - **Function**: A forward-biased diode allows current to flow in one direction but does not effectively filter out RF interference. It is primarily used for rectification, not for bypassing high-frequency noise.
  
- **D: Reverse-biased Diode**  
  - **Function**: A reverse-biased diode blocks current flow and does not provide a path for RF interference to ground. It is not useful for filtering purposes in this context.

### Summary
- **Bypass Capacitor**: Effective for shunting RF interference.
- **Bypass Inductor**: Blocks high frequencies, not useful here.
- **Forward-biased Diode**: Used for rectification, not filtering.
- **Reverse-biased Diode**: Blocks current, not effective for RF interference.

In summary, a bypass capacitor is the best choice for reducing RF interference in audio frequency circuits due to its ability to provide a low-impedance path for unwanted high-frequency signals.