which kind of wave would be observed in outer space between planets, where there is very little matter?\no…

which kind of wave would be observed in outer space between planets, where there is very little matter?\no an electromagnetic wave, such as an x - ray\no an electromagnetic wave, such as a sound wave\no a mechanical wave, such as an x - ray\no a mechanical wave, such as a sound wave
Answer
Brief Explanations:
Mechanical waves require a medium to travel, and there is little matter in outer - space between planets. Sound is a mechanical wave. Electromagnetic waves, like X - rays, can travel through a vacuum.
Answer:
an electromagnetic wave, such as an x - ray