The correct option is D Temperature of the medium
The velocity of sound is given by,
v=√γRTM
where γ is the adiabatic index, R is universal gas constant, T is absolute temperature and M is molecular mass of the gas.
So, speed of sound in a gaseous medium is independent of amplitude, frequency and phase angle of the sound wave and depends on the temperature of the medium.
Hence, option (d) is correct.