Answer:
Option (D)
Step-by-step explanation:
Refraction is defined as the process by which a wave changes its direction of propagation and bends towards the normal when moves from a rarer medium to a denser medium. The light after entering the new medium bends towards the normal. This process takes place due to the change in the wave speed and also due to the change in its wavelength.
As the waves enter a denser medium (such as glass) from the rarer medium (such as air), the wave speed decreases and so its wavelength also decreases. The speed and wavelength here are directly proportional to each other. It is because there are more particles in the denser medium that obstructs the direction of wave propagation.
Thus, the correct answer is an option (D).