the ability of electrons to travel through a medium the frequency of the wave the amplitude of the wave the proximity of the molecules of the medium
I gave my students this multiple choice question: Which of the following has the greatest effect on the speed at which sound travels through a gas?

Only one answer is correct among these 4 choices:
- the ability of electrons to travel through a medium
- the frequency of the wave
- the amplitude of the wave
- the proximity of the molecules of the medium

Could you tell me which one is correct?

the proximity of the molecules of the medium