*Question G7C13:
What term specifies a filter’s maximum ability to reject signals outside its passband?*  

*Correct Answer is  D: Ultimate rejection*  

### AI Response: (may contain errors)  

The term that specifies a filter’s maximum ability to reject signals outside its passband is known as **Ultimate rejection**.

### Explanation of the Correct Answer:
- **Ultimate rejection** refers to the maximum attenuation a filter can achieve for signals that fall outside its designated passband. This is a critical parameter for filters, as it indicates how effectively the filter can eliminate unwanted frequencies, ensuring that only the desired signals pass through.

### Why the Other Choices are Incorrect:
- **A: Notch depth**  
  - Notch depth refers to the amount of attenuation at the center frequency of a notch filter. It is specific to the frequency being rejected but does not describe the overall rejection capability of the filter across its entire stopband.

- **B: Rolloff**  
  - Rolloff describes the rate at which a filter attenuates signals as they move away from the passband. It is typically expressed in dB per octave or dB per decade, but it does not indicate the maximum rejection level.

- **C: Insertion loss**  
  - Insertion loss is the loss of signal power resulting from the insertion of a filter into a transmission line. It measures how much signal is lost when the filter is in place, but it does not relate to the filter's ability to reject signals outside the passband.

### Summary:
- The correct answer, **Ultimate rejection**, is the term that best describes a filter's maximum ability to reject unwanted signals outside its passband. Understanding these terms is essential for evaluating filter performance in radio communications.