Correct Option: C

Assuming air to be an ideal gas, the speed of sound depends on temperature only. As air temperature increases, so does the speed of sound and vice versa. The speed of sound is completely independent of air pressure because the air pressure and air density are proportional to each other at the same temperature. The speed of sound in air depends on the density of air which in turn depends on the temperature. The speed of a sound wave in air depends upon the properties of the air, mostly the temperature, and to a lesser degree, the humidity.