The speed of the wave mainly impacted by the properties of the medium.
Thus, the frequency, amplitude of the wave does not cause any impant on the speed of the sound wave traveling through the gas.
The sound wave is the transmission of the energy through the medium, thus, it does not depends upon the ability of electrons to travel through a medium.
Thus, the proximity of the molecules in the medium or the density of the medium effect the speed of the sound wave.
Hence, option D is the correct answer.
