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

*Correct Answer is  C: 525*  

### AI Response: (may contain errors)  

In the context of fast-scan (NTSC) television, the number of horizontal lines that make up a single frame is a key characteristic of the video format.

### Explanation:

1. **Correct Answer: 525**
   - The NTSC (National Television System Committee) standard for analog television specifies that each frame consists of 525 horizontal lines. This includes both the visible lines and the lines used for vertical blanking intervals, which are necessary for the electron beam in CRTs to return to the top of the screen.

2. **Why the Other Choices are Incorrect:**
   - **A: 30**  
     This number is incorrect because it refers to the frame rate of NTSC television, which is approximately 30 frames per second, not the number of lines per frame.
   
   - **B: 60**  
     This number is incorrect because it refers to the field rate in NTSC television. NTSC uses an interlaced scan, meaning each frame is made up of two fields, each with 262.5 lines, resulting in 60 fields per second.
   
   - **D: 1080**  
     This number is incorrect for NTSC. It refers to the number of lines in a high-definition television (HDTV) format, specifically 1080p or 1080i, which is not part of the NTSC standard.

### Additional Information:

- **Interlaced Scanning:**
  - NTSC uses interlaced scanning, where each frame is divided into two fields. Each field contains half of the lines (262.5 lines), and they are displayed alternately to create the perception of a full frame.

Understanding these details helps clarify why 525 is the correct number of horizontal lines in an NTSC television frame.