An astronaut can't hear his companion at the surface of the moon because :

Options

A. produced frequencies are above the audio frequency
B. there is no medium for sound propagation
C. temperature is too low during night and too high during day
D. there are too many craters on the surface of the moon

Explanation

**Step-by-Step Solution:**

1. **Understanding Sound Propagation**: Sound is a mechanical wave that requires a medium (solid, liquid, or gas) to travel through. Without a medium, sound cannot propagate.

2. **Conditions on the Moon**: The Moon has a very thin atmosphere, which is almost a vacuum. This means there is insufficient air or any other material medium for sound waves to travel through.

3. **Conclusion**: Since sound cannot travel through a vacuum and the Moon lacks a significant atmosphere, an astronaut cannot hear his companion at the surface of the Moon.

4. **Final Answer**: An astronaut can't hear his companion at the surface of the Moon because there is no medium for sound propagation.

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