Correct Answer: (b) The speed of sound waves in air decreases with increase in temperature.
Solution:The speed of sound is directly proportional to the temperature. Therefore, as the temperature increases, the speed of sound increases. The speed of the sound also depends on the density of the medium through which it travels. In general, sound travels faster in liquids (like water) than in gases (like air) and quicker in solids (like steel) than in liquids.