*Question E2B02:
How many horizontal lines make up a fast-scan (NTSC) television frame?*  

*Correct Answer is  C: 525*  

### AI Response: (may contain errors)  

To determine how many horizontal lines make up a fast-scan (NTSC) television frame, we refer to the standard specifications for NTSC video.

1. **Correct Answer Explanation:**
   - The correct answer is **525**. An NTSC television frame consists of 525 horizontal scan lines. This includes both visible lines and those used for synchronization.

2. **Incorrect Choices Explanation:**
   - **A: 30**: This number is far too low. It does not represent any standard for television frames.
   - **B: 60**: This number refers to the frame rate (60 fields per second) in interlaced scanning, not the number of lines.
   - **D: 1080**: This number corresponds to the vertical resolution of high-definition television (HDTV) formats, specifically 1080p, which is not applicable to NTSC.

3. **Useful Information:**
   - NTSC uses interlaced scanning, where each frame consists of two fields. Each field contains 262.5 lines, and when combined, they create the full 525 lines for one complete frame.
   - The formula for the total number of lines in an NTSC frame can be summarized as:
   $$\text{Total Lines} = \text{Lines per Field} \times 2$$
   where:
   - Lines per Field = 262.5 (for NTSC)

This understanding of NTSC standards is crucial for the Extra Class exam and helps clarify the structure of television signals.