33. An engineer is calibrating an acoustic sensor on the surface of Mars. The Martian atmosphere is primarily composed of carbon dioxide, whereas Earth's atmosphere consists mainly of dinitrogen and dioxygen. Sound waves propagate as rapid compressions and rarefactions under conditions where heat transfer is negligible (i.e., adiabatic propagation). If the engineer compares a sample of Martian air with a sample of Earth air at the same temperature, which of the following is the dominant factor explaining why the speed of sound is lower on Mars?
(A) CO2 has a higher molar mass than N2 or O2.
(B) CO2 has a higher heat capacity ratio (Cp/Cy) due to more degrees of freedom.
(C) The Martian atmosphere is thinner, and the lower pressure P reduces the bulk modulus.
(D) The heat conduction of CO2 is much poorer than that of N2 or O2 for the same temperature.
(E) The gravity on Mars is lower than that on Earth.