*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, an interlaced scanning pattern is used to create a complete image by dividing it into two separate fields. Here's how it works:

1. **Correct Answer: D**  
   - **Explanation**: The interlaced scanning pattern is generated by scanning odd-numbered lines in one field and even-numbered lines in the next. This means that the first field contains lines 1, 3, 5, etc., while the second field contains lines 2, 4, 6, etc. When these two fields are displayed in rapid succession, they combine to form a complete frame. This method reduces flicker and conserves bandwidth by effectively doubling the perceived frame rate without increasing the actual number of frames transmitted per second.

2. **Why the Other Choices are Incorrect**:
   - **Choice A**: "By scanning two fields simultaneously" is incorrect because interlaced scanning involves sequentially displaying two fields, not simultaneously. Each field is displayed one after the other to create the perception of a complete image.
   - **Choice B**: "By scanning each field from bottom-to-top" is incorrect because NTSC scanning is done from top-to-bottom, not bottom-to-top. Each line is scanned horizontally from left to right.
   - **Choice C**: "By scanning lines from left-to-right in one field and right-to-left in the next" is incorrect because all lines in both fields are scanned from left to right. The direction of scanning does not change between fields.

3. **Useful Rule of Thumb**:
   - In NTSC interlaced scanning, each complete frame consists of two fields: one with odd-numbered lines and one with even-numbered lines. This technique helps in reducing the bandwidth required for transmission while maintaining a smooth visual experience.