*Question E2B01:
In digital television, what does a coding rate of 3/4 mean?*  

*Correct Answer is  A: 25% of the data sent is forward error correction data*  

### AI Response: (may contain errors)  

In digital television, a coding rate of 3/4 indicates the proportion of the transmitted data that is actual information versus error correction data.

### Explanation of the Correct Answer:
- **Correct Answer: A: 25% of the data sent is forward error correction data**
  - A coding rate of 3/4 means that for every 4 bits transmitted, 3 bits are actual data, and 1 bit is used for error correction. This implies that 25% of the transmitted data is dedicated to forward error correction (FEC). The coding rate can be interpreted as:
  
  $$ \text{FEC Data} = 1 - \text{Coding Rate} = 1 - \frac{3}{4} = \frac{1}{4} $$

### Explanation of Incorrect Answers:
- **B: Data compression reduces data rate by 3/4**
  - This statement is incorrect because the coding rate does not refer to data compression. Instead, it specifically relates to the ratio of useful data to error correction data in the transmission.

- **C: 1/4 of the time interval is used as a guard interval**
  - This is incorrect as the coding rate does not define the time interval for guard intervals. Guard intervals are used to prevent inter-symbol interference and are not directly related to the coding rate.

- **D: Three, four-bit words are used to transmit each pixel**
  - This statement is misleading. The coding rate does not specify the number of bits used to represent a pixel. It only indicates the ratio of data to error correction bits in the transmission.

### Summary:
- A coding rate of 3/4 means that 25% of the data sent is for error correction, ensuring reliable transmission despite potential errors. Understanding coding rates is crucial for grasping how digital signals maintain integrity during transmission.