*Question E2B03:
How is an interlaced scanning pattern generated in a fast-scan (NTSC) television system?*  

*Correct Answer is  D: By scanning odd-numbered lines in one field and even-numbered lines in the next*  

### AI Response: (may contain errors)  

In a fast-scan (NTSC) television system, the interlaced scanning pattern is crucial for displaying images smoothly. Let's break down the correct answer and why the other options are incorrect.

### Correct Answer: 
**D: By scanning odd-numbered lines in one field and even-numbered lines in the next.**

- **Explanation**: 
  - In an interlaced scanning system, the image is divided into two fields. The first field consists of all the odd-numbered lines (1, 3, 5, ...), and the second field consists of all the even-numbered lines (2, 4, 6, ...). 
  - This method allows for a smoother image display because it effectively doubles the perceived frame rate without requiring more bandwidth. Each field is displayed in rapid succession, creating the illusion of a complete image.

### Why the Other Choices are Incorrect:

- **A: By scanning two fields simultaneously**  
  - **Incorrect**: Interlaced scanning does not involve scanning both fields at the same time. Instead, it alternates between the two fields, which is what creates the interlaced effect.

- **B: By scanning each field from bottom-to-top**  
  - **Incorrect**: In NTSC systems, fields are scanned from top-to-bottom, not bottom-to-top. This is a standard scanning direction for television systems.

- **C: By scanning lines from left-to-right in one field and right-to-left in the next**  
  - **Incorrect**: The scanning direction for each field is consistently left-to-right. There is no reversal of direction between fields in the NTSC system.

### Summary:
- Interlaced scanning improves image quality by alternating between odd and even lines, enhancing the visual experience without increasing bandwidth requirements. Understanding this concept is essential for the Extra Class exam, as it highlights the principles of video transmission and display technology.