Answer:
velocity and wavelength
Step-by-step explanation:
When a ray of light moves from one medium to another, the ray of light changes the direction when it enters the second medium, refraction of light occurs.
When it changes the direction, the frequency will remain the same because it depends only on the source not on the medium.
As the refractive index of two medium is not same, it means the wavelength will change.
Also, speed = frequency × wavelength
So, wavelength and velocity changes. Hence, the correct option is (a).