The correct answer is option 4 - Both (2,3).
Option 1 states that the sound moves with higher velocity if the pressure of the medium is decreased. This is incorrect because the velocity of sound is not directly influenced by the pressure of the medium. While changes in pressure can affect the speed of sound to some extent, it is generally a minimal effect compared to other factors.
Option 2 states that the sound moves with higher velocity if the temperature of the medium is increased. This is correct. The speed of sound is directly proportional to the square root of the temperature of the medium. As the temperature increases, the particles of the medium vibrate more vigorously, leading to a higher speed of sound.
Option 3 states that the sound moves with higher velocity if the humidity of the medium is increased. This is incorrect. Humidity, which refers to the amount of water vapor in the air, does not have a significant impact on the speed of sound. The speed of sound is primarily determined by properties such as temperature, density, and elasticity of the medium.
In conclusion, option 4 is the correct answer because the speed of sound does increase with higher temperature, but it is not influenced by changes in humidity or pressure.