The correct answer is option A) An electromagnetic wave, such as an x-ray.
Explanation-
Sound wave is a mechanical wave, which needs a medium for its propagation. There is no medium between planets that is it is an empty space or vacuum.
Hence, sound wave can not propagate in between planets.
X ray is an electromagnetic wave, which needs no medium for its propagation. It can travel in space with the velocity of light.
Thus, the correct option is A).