Answer: Diffraction
Explanation:
-Diffraction, is basically the bending of waves as they move around an obstacle or through an opening. In both, the cases diffraction occurs. So as the waves hit the obstacle they will bend slightly around it.
The other options, for a better understanding why it's option A:
-Interference occurs when two waves at one point or another in the same medium, overlap
-Refraction of waves is the change in its direction when it moves from one medium to another. The other factors that change with refraction are the wavelength.
