Long range transmission of TV-signal is done by

Options

A. space-wave
B. sky waves
C. ground wave
D. artificial satellite

Explanation

To determine the method used for long-range transmission of TV signals, we can analyze the options provided:

1. **Understanding the Options**:
- **A. Space Wave**: This involves transmission through the atmosphere and is typically used for line-of-sight communication. However, it has limited range due to the curvature of the Earth.
- **B. Sky Wave**: This refers to signals that are reflected off the ionosphere. It can cover longer distances but is generally used for lower frequency signals.
- **C. Ground Wave**: This travels along the surface of the Earth and can cover some distance, but it is also limited in range, especially for higher frequencies.
- **D. Artificial Satellite**: This method involves transmitting signals from satellites in space, allowing for coverage over vast distances and through various terrains.

2. **Frequency Consideration**:
- TV signals typically operate in the frequency range of 30-300 MHz.
- The ground wave and space wave methods are less effective for these higher frequencies, while the sky wave can reflect signals but is not as reliable for the higher frequency range used by TV signals.

3. **Conclusion**:
- Given that artificial satellites can effectively transmit and receive signals at the required frequency range and cover long distances without the limitations faced by the other methods, the correct answer is **D. Artificial Satellite**.

### Step-by-Step Solution:
1. **Identify the frequency range of TV signals**: TV signals operate between 30-300 MHz.
2. **Evaluate each transmission method**:
- Space Wave: Limited by line-of-sight and curvature of the Earth.
- Sky Wave: Can reflect signals but is more suited for lower frequencies.
- Ground Wave: Travels along the surface but is limited for higher frequencies.
- Artificial Satellite: Can transmit signals over long distances and effectively handle the required frequency range.
3. **Determine the best option**: Since artificial satellites can handle the higher frequency range and provide long-range transmission, they are the most suitable choice for TV signal transmission.

### Final Answer:
The long-range transmission of TV signals is done by **D. Artificial Satellite**.