Answer:
C. The frequency stays the same and the wavelength decreases
Step-by-step explanation:
The speed of a wave, 'v', is given as follows;
v = Frequency, f × Wavelength, λ
∴ v = f × λ
Therefore, the speed of the wave is directly proportional to the wavelength
v ∝ λ
When the speed of the sound wave increases as it enters a new medium, we have that frequency of the wave, which is determined at the source, remains the same, while the wavelength of the wave increases
As 'v' increases, λ increases
Therefore, for an increase in velocity of the wave, the frequency of the wave stays the same and the wavelength increases.